LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 LM2594/LM2594HV SIMPLE SWITCHER(R) Power Converter 150 kHz 0.5A Step-Down Voltage Regulator Check for Samples: LM2594, LM2594HV FEATURES DESCRIPTION * 3.3V, 5V, 12V, and Adjustable Output Versions * Adjustable Version Output Voltage Range, 1.2V to 37V (57V for the HV Version)4% Max Over Line and Load Conditions * Available in 8-pin Surface Mount SOIC and PDIP-8 Package * Ensured 0.5A Output Current * Input Voltage Range up to 60V * Requires only 4 External Components * 150 kHz Fixed Frequency Internal Oscillator * TTL Shutdown Capability * Low Power Standby Mode, IQ typically 85 A * High Efficiency * Uses Readily Available Standard Inductors * Thermal Shutdown and Current Limit Protection The LM2594/LM2594HV series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 0.5A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, and an adjustable output version, and are packaged in a 8-lead PDIP and a 8-lead surface mount SOIC package. 1 2345 APPLICATIONS * * * * Simple High-efficiency Step-down (Buck) Regulator Efficient Pre-regulator for Linear Regulators On-card Switching Regulators Positive to Negative Convertor Requiring a minimum number of external components, these regulators are simple to use and feature internal frequency compensation, a fixedfrequency oscillator, and improved line and load regulation specifications. The LM2594/LM2594HV series operates at a switching frequency of 150 kHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Because of its high efficiency, the copper traces on the printed circuit board are normally the only heat sinking needed. A standard series of inductors (both through hole and surface mount types) are available from several different manufacturers optimized for use with the LM2594/LM2594HV series. This feature greatly simplifies the design of switch-mode power supplies. Other features include an ensured 4% tolerance on output voltage under all conditions of input voltage and output load conditions, and 15% on the oscillator frequency. External shutdown is included, featuring typically 85 A standby current. Self protection features include a two stage frequency reducing current limit for the output switch and an over temperature shutdown for complete protection under fault conditions. The LM2594HV is for applications requiring an input voltage up to 60V. 1 2 3 4 5 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Switchers Made Simple is a trademark of Texas Instruments. SIMPLE SWITCHER is a registered trademark of Texas Instruments. Switchers Made Simple is a registered trademark of dcl_owner. All other trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright (c) 1999-2013, Texas Instruments Incorporated LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Typical Application (Fixed Output Voltage Versions) Connection Diagrams and Order Information Figure 1. 8-Pin - Top View See Package Number P0008E Figure 2. 8-Pin - Top View See Package Number D0008A *No internal connection, but should be soldered to pc board for best heat transfer. Patent Number 5,382,918. 2 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) Maximum Supply Voltage LM2594 45V LM2594HV 60V ON /OFF Pin Input Voltage -0.3 V +25V Feedback Pin Voltage -0.3 V +25V -1V Output Voltage to Ground (Steady State) Power Dissipation Internally limited -65C to +150C Storage Temperature Range ESD Susceptibility Human Body Model (3) 2 kV Vapor Phase (60 sec.) +215C Infrared (15 sec.) +220C Lead Temperature D8 Package P Package (Soldering, 10 sec.) +260C Maximum Junction Temperature +150C (1) (2) (3) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not ensure specific performance limits. For ensured specifications and test conditions, see the Electrical Characteristics. If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications. The human body model is a 100 pF capacitor discharged through a 1.5k resistor into each pin. Operating Conditions -40C TJ +125C Temperature Range Supply Voltage LM2594 4.5V to 40V LM2594HV 4.5V to 60V LM2594/LM2594HV-3.3 Electrical Characteristics Specifications with standard type face are for TJ = 25C, and those with boldface type apply over full Operating Temperature Range.VINmax= 40V for the LM2594 and 60V for the LM2594HV. Symbol Parameter Conditions LM2594/LM2594HV-3.3 Typ (1) Limit (2) Units (Limits) SYSTEM PARAMETERS (3) Test Circuit Figure 20 VOUT Output Voltage 4.75V VIN VINmax, 0.1A ILOAD 0.5A 3.3 3.432/3.465 3.168/3.135 (1) (2) (3) Efficiency VIN = 12V, ILOAD = 0.5A V V(min) V(max) 80 % Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator system performance. When the LM2594/LM2594HV is used as shown in the Figure 20 test circuit, system performance will be as shown in system parameters section of Electrical Characteristics. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 3 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com LM2594/LM2594HV-5.0 Electrical Characteristics Specifications with standard type face are for TJ = 25C, and those with boldface type apply over full Operating Temperature Range Symbol Parameter Conditions LM2594/LM2594HV-5.0 Typ (1) Limit (2) Units (Limits) SYSTEM PARAMETERS (3) Test Circuit Figure 20 VOUT Output Voltage 7V VIN VINmax, 0.1A ILOAD 0.5A 5.0 4.800/4.750 5.200/5.250 Efficiency (1) (2) (3) VIN = 12V, ILOAD = 0.5A 82 V V(min) V(max) % Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator system performance. When the LM2594/LM2594HV is used as shown in the Figure 20 test circuit, system performance will be as shown in system parameters section of Electrical Characteristics. LM2594/LM2594HV-12 Electrical Characteristics Specifications with standard type face are for TJ = 25C, and those with boldface type apply over full Operating Temperature Range Symbol Parameter Conditions LM2594/LM2594HV-12 Typ (1) Limit (2) Units (Limits) SYSTEM PARAMETERS (3) Test Circuit Figure 20 VOUT Output Voltage 15V VIN VINmax, 0.1A ILOAD 0.5A Efficiency VIN = 25V, ILOAD = 0.5A 12.0 11.52/11.40 12.48/12.60 (1) (2) (3) 88 V V(min) V(max) % Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator system performance. When the LM2594/LM2594HV is used as shown in the Figure 20 test circuit, system performance will be as shown in system parameters section of Electrical Characteristics. LM2594/LM2594HV-ADJ Electrical Characteristics Specifications with standard type face are for TJ = 25C, and those with boldface type apply over full Operating Temperature Range Symbol Parameter Conditions LM2594/LM2594HV-ADJ Typ (1) Limit (2) Units (Limits) SYSTEM PARAMETERS (3) Test Circuit Figure 20 VFB Feedback Voltage 4.5V VIN VINmax, 0.1A ILOAD 0.5A VOUT programmed for 3V. Circuit of Figure 20 Efficiency VIN = 12V, ILOAD = 0.5A (1) (2) (3) 4 1.230 1.193/1.180 1.267/1.280 80 V V(min) V(max) % Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator system performance. When the LM2594/LM2594HV is used as shown in the Figure 20 test circuit, system performance will be as shown in system parameters section of Electrical Characteristics. Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 All Output Voltage Versions Electrical Characteristics Specifications with standard type face are for TJ = 25C, and those with boldface type apply over full Operating Temperature Range . Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V version. ILOAD = 100 mA Symbol Parameter Conditions LM2594/LM2594HV-XX Typ (1) Limit (2) 50/100 Units (Limits) DEVICE PARAMETERS Ib Feedback Bias Current Adjustable Version Only, VFB = 1.3V 10 fO Oscillator Frequency See (3) 150 VSAT DC ICL Saturation Voltage IOUT = 0.5A (4) (5) Max Duty Cycle (ON) See (5) Min Duty Cycle (OFF) See (6) Current Limit Peak Current (4) (5) 127/110 kHz(min) 173/173 kHz(max) 1.1/1.2 V(max) 0.9 V 100 % 0 0.8 A 0.65/0.58 IL Output Leakage Current IQ Quiescent Current ISTBY Standby Quiescent Current Output = 0V (4) (6) (7) Output = -1V See (6) mA 15 mA(max) 10 mA(max) mA A 200/250 140 P Package, Junction to Ambient (8) MDPackage, Junction to Ambient A(max) 85 LM2594HV Thermal Resistance A(max) 50 5 ON/OFF pin = 5V (OFF) (7) (8) A(min) 1.3/1.4 2 LM2594 JA nA kHz 250/300 95 A(max) A(max) C/W 150 ON/OFF CONTROL Test Circuit Figure 20 ON /OFF Pin Logic Input VIH Threshold Voltage VIL IH IL (1) (2) (3) (4) (5) (6) (7) (8) ON /OFF Pin Input Current 1.3 V Low (Regulator ON) 0.6 V(max) High (Regulator OFF) 2.0 V(min) 15 A(max) 5 A(max) VLOGIC = 2.5V (Regulator OFF) VLOGIC = 0.5V (Regulator ON) A 5 A 0.02 Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). The switching frequency is reduced when the second stage current limit is activated. The amount of reduction is determined by the severity of current overload. No diode, inductor or capacitor connected to output pin. Feedback pin removed from output and connected to 0V to force the output transistor switch ON. Feedback pin removed from output and connected to 12V for the 3.3V, 5V, and the ADJ. version, and 15V for the 12V version, to force the output transistor switch OFF. VIN = 40V for the LM2594 and 60V for the LM2594HV. Junction to ambient thermal resistance with approximately 1 square inch of printed circuit board copper surrounding the leads. Additional copper area will lower thermal resistance further. See application hints in this data sheet and the thermal model in Switchers Made Simple(R) software. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 5 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics 6 Normalized Output Voltage Line Regulation Figure 3. Figure 4. Efficiency Switch Saturation Voltage Figure 5. Figure 6. Switch Current Limit Dropout Voltage Figure 7. Figure 8. Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Typical Performance Characteristics (continued) Quiescent Current Standby Quiescent Current Figure 9. Figure 10. Minimum Operating Supply Voltage ON /OFF Threshold Voltage Figure 11. Figure 12. ON /OFF Pin Current (Sinking) Switching Frequency Figure 13. Figure 14. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 7 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Feedback Pin Bias Current Figure 15. 8 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Typical Performance Characteristics Continuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 400 mA L = 100 H, COUT = 120 F, COUT ESR = 140 m A: Output Pin Voltage, 10V/div. B: Inductor Current 0.2A/div. C: Output Ripple Voltage, 20 mV/div. Figure 16. Horizontal Time Base: 2 s/div. Load Transient Response for Continuous Mode VIN = 20V, VOUT = 5V, ILOAD = 200 mA to 500 mA L = 100 H, COUT = 120 F, COUT ESR = 140 m A: Output Voltage, 50 mV/div. (AC) B: 200 mA to 500 mA Load Pulse Figure 18. Horizontal Time Base: 50 s/div. Discontinuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 200 mA L = 33 H, COUT = 220 F, COUT ESR = 60 m A: Output Pin Voltage, 10V/div. B: Inductor Current 0.2A/div. C: Output Ripple Voltage, 20 mV/div. Figure 17. Horizontal Time Base: 2 s/div. Load Transient Response for Discontinuous Mode VIN = 20V, VOUT = 5V, ILOAD = 100 mA to 200 mA L = 33 H, COUT = 220 F, COUT ESR = 60 m A: Output Voltage, 50 mV/div. (AC) B: 100 mA to 200 mA Load Pulse Figure 19. Horizontal Time Base: 200 s/div. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 9 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com TYPICAL CIRCUIT AND LAYOUT GUIDELINES Fixed Output Voltage Versions CIN -- 68 F, 35V, Aluminum Electrolytic Nichicon "PL Series" COUT -- 120 F, 25V Aluminum Electrolytic, Nichicon "PL Series" D1 -- 1A, 40V Schottky Rectifier, 1N5819 L1 -- 100 H, L20 Select components with higher voltage ratings for designs using the LM2594HV with an input voltage between 40V and 60V. Adjustable Output Voltage Versions CIN -- 68 F, 35V, Aluminum Electrolytic Nichicon "PL Series" COUT -- 120 F, 25V Aluminum Electrolytic, Nichicon "PL Series" D1 -- 1A, 40V Schottky Rectifier, 1N5819 L1 -- 100 H, L20 R1 -- 1 k, 1% CFF -- See Application Information Section Figure 20. Typical Circuits and Layout Guides As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance can generate voltage transients which can cause problems. For minimal inductance and ground loops, the wires indicated by heavy lines should be wide printed circuit traces and should be kept as short as possible. For best results, external components should be located as close to the switcher lC as possible using ground plane construction or single point grounding. If open core inductors are used, special care must be taken as to the location and positioning of this type of inductor. Allowing the inductor flux to intersect sensitive feedback, lC groundpath and COUT wiring can cause problems. 10 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 When using the adjustable version, special care must be taken as to the location of the feedback resistors and the associated wiring. Physically locate both resistors near the IC, and route the wiring away from the inductor, especially an open core type of inductor. (See Application Information section for more information.) Table 1. LM2594/LM2594HV Series Buck Regulator Design Procedure (Fixed Output) PROCEDURE (Fixed Output Voltage Version) EXAMPLE (Fixed Output Voltage Version) Given: VOUT = Regulated Output Voltage (3.3V, 5V or 12V) VIN(max) = Maximum DC Input Voltage ILOAD(max) = Maximum Load Current Given: VOUT = 5V VIN(max) = 12V ILOAD(max) = 0.4A 1. Inductor Selection (L1) A. Select the correct inductor value selection guide from Figure 21 Figure 22 or Figure 23. (Output voltages of 3.3V, 5V, or 12V respectively.) For all other voltages, see the design procedure for the adjustable version. B. From the inductor value selection guide, identify the inductance region intersected by the Maximum Input Voltage line and the Maximum Load Current line. Each region is identified by an inductance value and an inductor code (LXX). C. Select an appropriate inductor from the four manufacturer's part numbers listed in Table 5. 1. Inductor Selection (L1) A. Use the inductor selection guide for the 5V version shown in Figure 22. B. From the inductor value selection guide shown in Figure 22, the inductance region intersected by the 12V horizontal line and the 0.4A vertical line is 100 H, and the inductor code is L20. C. The inductance value required is 100 H. From Table 5, go to the L20 line and choose an inductor part number from any of the four manufacturers shown. (In most instance, both through hole and surface mount inductors are available.) 2. Output Capacitor Selection (COUT) A. In the majority of applications, low ESR (Equivalent Series Resistance) electrolytic capacitors between 82 F and 220 F and low ESR solid tantalum capacitors between 15 F and 100 F provide the best results. This capacitor should be located close to the IC using short capacitor leads and short copper traces. Do not use capacitors larger than 220 F. For additional information, see OUTPUT CAPACITOR section in Application Information section. B. To simplify the capacitor selection procedure, refer to the quick design component selection table shown in Figure 24. This table contains different input voltages, output voltages, and load currents, and lists various inductors and output capacitors that will provide the best design solutions. C. The capacitor voltage rating for electrolytic capacitors should be at least 1.5 times greater than the output voltage, and often much higher voltage ratings are needed to satisfy the low ESR requirements for low output ripple voltage. D. For computer aided design software, see Switchers Made SimpleTM version 4.1 or later. 2. Output Capacitor Selection (COUT) A. See OUTPUT CAPACITOR section in Application Information section. B. From the quick design component selection table shown in Figure 24, locate the 5V output voltage section. In the load current column, choose the load current line that is closest to the current needed in your application, for this example, use the 0.5A line. In the maximum input voltage column, select the line that covers the input voltage needed in your application, in this example, use the 15V line. Continuing on this line are recommended inductors and capacitors that will provide the best overall performance. The capacitor list contains both through hole electrolytic and surface mount tantalum capacitors from four different capacitor manufacturers. It is recommended that both the manufacturers and the manufacturer's series that are listed in the table be used. In this example aluminum electrolytic capacitors from several different manufacturers are available with the range of ESR numbers needed. 120 F 25V Panasonic HFQ Series 120 F 25V Nichicon PL Series C. For a 5V output, a capacitor voltage rating at least 7.5V or more is needed. But, in this example, even a low ESR, switching grade, 120 F 10V aluminum electrolytic capacitor would exhibit approximately 400 m of ESR (see the curve in Figure 26 for the ESR vs voltage rating). This amount of ESR would result in relatively high output ripple voltage. To reduce the ripple to 1% of the output voltage, or less, a capacitor with a higher voltage rating (lower ESR) should be selected. A 16V or 25V capacitor will reduce the ripple voltage by approximately half. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 11 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Table 1. LM2594/LM2594HV Series Buck Regulator Design Procedure (Fixed Output) (continued) PROCEDURE (Fixed Output Voltage Version) EXAMPLE (Fixed Output Voltage Version) 3. Catch Diode Selection (D1) A. The catch diode current rating must be at least 1.3 times greater than the maximum load current. Also, if the power supply design must withstand a continuous output short, the diode should have a current rating equal to the maximum current limit of the LM2594. The most stressful condition for this diode is an overload or shorted output condition. B. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. C. This diode must be fast (short reverse recovery time) and must be located close to the LM2594 using short leads and short printed circuit traces. Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best performance and efficiency, and should be the first choice, especially in low output voltage applications. Ultra-fast recovery, or High-Efficiency rectifiers also provide good results. Ultra-fast recovery diodes typically have reverse recovery times of 50 ns or less. Rectifiers such as the 1N4001 series are much too slow and should not be used. 3. Catch Diode Selection (D1) A. Refer to the table shown in Table 8. In this example, a 1A, 20V, 1N5817 Schottky diode will provide the best performance, and will not be overstressed even for a shorted output. 4. Input Capacitor (CIN) A low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground to prevent large voltage transients from appearing at the input. In addition, the RMS current rating of the input capacitor should be selected to be at least 1/2 the DC load current. The capacitor manufacturers data sheet must be checked to assure that this current rating is not exceeded. The curve shown in Figure 25 shows typical RMS current ratings for several different aluminum electrolytic capacitor values. This capacitor should be located close to the IC using short leads and the voltage rating should be approximately 1.5 times the maximum input voltage. If solid tantalum input capacitors are used, it is recommended that they be surge current tested by the manufacturer. Use caution when using ceramic capacitors for input bypassing, because it may cause severe ringing at the VIN pin. For additional information, see EXTERNAL COMPONENTS section on input capacitors in Application Information section. 4. Input Capacitor (CIN) The important parameters for the Input capacitor are the input voltage rating and the RMS current rating. With a nominal input voltage of 12V, an aluminum electrolytic capacitor with a voltage rating greater than 18V (1.5 x VIN) would be needed. The next higher capacitor voltage rating is 25V. The RMS current rating requirement for the input capacitor in a buck regulator is approximately 1/2 the DC load current. In this example, with a 400 mA load, a capacitor with a RMS current rating of at least 200 mA is needed. The curves shown in Figure 25 can be used to select an appropriate input capacitor. From the curves, locate the 25V line and note which capacitor values have RMS current ratings greater than 200 mA. Either a 47 F or 68 F, 25V capacitor could be used. For a through hole design, a 68 F/25V electrolytic capacitor (Panasonic HFQ series or Nichicon PL series or equivalent) would be adequate. Other types or other manufacturers capacitors can be used provided the RMS ripple current ratings are adequate. For surface mount designs, solid tantalum capacitors are recommended. The TPS series available from AVX, and the 593D series from Sprague are both surge current tested. Table 2. LM2594/LM2594HV Fixed Voltage Quick Design Component Selection Table Conditions Inductor Output Capacitor Through Hole Surface Mount Output Load Max Input Inductance Inductor Panasonic Nichicon AVX TPS Sprague Voltage Current Voltage (H) (#) HFQ Series PL Series Series 595D Series (V) (A) (V) (F/V) (F/V) (F/V) (F/V) 3.3 0.5 5 33 L14 220/16 220/16 100/16 100/6.3 7 47 L13 120/25 120/25 100/16 100/6.3 10 68 L21 120/25 120/25 100/16 100/6.3 40 100 L20 120/35 120/35 100/16 100/6.3 0.2 12 6 68 L4 120/25 120/25 100/16 100/6.3 10 150 L10 120/16 120/16 100/16 100/6.3 40 220 L9 120/16 120/16 100/16 100/6.3 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Table 2. LM2594/LM2594HV Fixed Voltage Quick Design Component Selection Table (continued) Conditions Inductor Output Capacitor Through Hole Surface Mount Output Load Max Input Inductance Inductor Panasonic Nichicon AVX TPS Sprague Voltage Current Voltage (H) (#) HFQ Series PL Series Series 595D Series (V) (A) (V) (F/V) (F/V) (F/V) (F/V) 5 0.5 0.2 12 0.5 0.2 8 47 L13 180/16 180/16 100/16 33/25 10 68 L21 180/16 180/16 100/16 33/25 15 100 L20 120/25 120/25 100/16 33/25 40 150 L19 120/25 120/25 100/16 33/25 9 150 L10 82/16 82/16 100/16 33/25 20 220 L9 120/16 120/16 100/16 33/25 40 330 L8 120/16 120/16 100/16 33/25 15 68 L21 82/25 82/25 100/16 15/25 18 150 L19 82/25 82/25 100/16 15/25 30 220 L27 82/25 82/25 100/16 15/25 40 330 L26 82/25 82/25 100/16 15/25 15 100 L11 82/25 82/25 100/16 15/25 20 220 L9 82/25 82/25 100/16 15/25 40 330 L17 82/25 82/25 100/16 15/25 Table 3. LM2594/LM2594HV Series Buck Regulator Design Procedure (Adjustable Output) PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable Output Voltage Version) Given: VOUT = Regulated Output Voltage VIN(max) = Maximum Input Voltage ILOAD(max) = Maximum Load Current F = Switching Frequency (Fixed at a nominal 150 kHz). Given: VOUT = 20V VIN(max) = 28V ILOAD(max) = 0.5A F = Switching Frequency (Fixed at a nominal 150 kHz). 1. Programming Output Voltage (Selecting R1 and R2, as shown in 1. Programming Output Voltage (Selecting R1 and R2, as shown in Figure 20. Figure 20 ) Use the following formula to select the appropriate resistor values. Select R1 to be 1 k, 1%. Solve for R2. (3) (1) Select a value for R1 between 240 and 1.5 k. The lower resistor R2 = 1k (16.26 - 1) = 15.26k, closest 1% value is 15.4 k. values minimize noise pickup in the sensitive feedback pin. (For the R = 15.4 k. 2 lowest temperature coefficient and the best stability with time, use 1% metal film resistors.) (2) Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 13 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Table 3. LM2594/LM2594HV Series Buck Regulator Design Procedure (Adjustable Output) (continued) PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable Output Voltage Version) 2. Inductor Selection (L1) 2. Inductor Selection (L1) A. Calculate the inductor Volt microsecond constant E * T (V * s) , A. Calculate the inductor Volt * microsecond constant (E * T) , from the following formula: (4) where VSAT = internal switch saturation voltage = 0.9V and VD = diode forward voltage drop = 0.5V B. Use the E * T value from the previous formula and match it with the E * T number on the vertical axis of the Inductor Value Selection Guide shown in Figure 24. C. on the horizontal axis, select the maximum load current. D. Identify the inductance region intersected by the E * T value and the Maximum Load Current value. Each region is identified by an inductance value and an inductor code (LXX). E. Select an appropriate inductor from the four manufacturer's part numbers listed in Table 5. (5) B. E * T = 35.2 (V * s) C. ILOAD(max) = 0.5A D. From the inductor value selection guide shown in Figure 24, the inductance region intersected by the 35 (V * s) horizontal line and the 0.5A vertical line is 150 H, and the inductor code is L19. E. From Table 5, locate line L19, and select an inductor part number from the list of manufacturers part numbers. 3. Output Capacitor Selection (COUT) A. In the majority of applications, low ESR electrolytic or solid tantalum capacitors between 82 F and 220 F provide the best results. This capacitor should be located close to the IC using short capacitor leads and short copper traces. Do not use capacitors larger than 220 F. For additional information, see OUTPUT CAPACITOR section in Application Information section. B. To simplify the capacitor selection procedure, refer to the quick design table shown in Table 4. This table contains different output voltages, and lists various output capacitors that will provide the best design solutions. C. The capacitor voltage rating should be at least 1.5 times greater than the output voltage, and often much higher voltage ratings are needed to satisfy the low ESR requirements needed for low output ripple voltage. 3. Output Capacitor SeIection (COUT) A. See OUTPUT CAPACITORsection on COUT in Application Information section. B. From the quick design table shown in Table 4, locate the output voltage column. From that column, locate the output voltage closest to the output voltage in your application. In this example, select the 24V line. Under the OUTPUT CAPACITORoutput capacitor, select a capacitor from the list of through hole electrolytic or surface mount tantalum types from four different capacitor manufacturers. It is recommended that both the manufacturers and the manufacturers series that are listed in the table be used. In this example, through hole aluminum electrolytic capacitors from several different manufacturers are available. 82 F 50V Panasonic HFQ Series 120 F 50V Nichicon PL Series C. For a 20V output, a capacitor rating of at least 30V or more is needed. In this example, either a 35V or 50V capacitor would work. A 50V rating was chosen because it has a lower ESR which provides a lower output ripple voltage. Other manufacturers or other types of capacitors may also be used, provided the capacitor specifications (especially the 100 kHz ESR) closely match the types listed in the table. Refer to the capacitor manufacturers data sheet for this information. 4. Feedforward Capacitor (CFF) (See Figure 20 ) For output voltages greater than approximately 10V, an additional capacitor is required. The compensation capacitor is typically between 50 pF and 10 nF, and is wired in parallel with the output voltage setting resistor, R2. It provides additional stability for high output voltages, low input-output voltages, and/or very low ESR output capacitors, such as solid tantalum capacitors. 4. Feedforward Capacitor (CFF) The table shown in Table 4 contains feed forward capacitor values for various output voltages. In this example, a 1 nF capacitor is needed. (6) This capacitor type can be ceramic, plastic, silver mica, etc. (Because of the unstable characteristics of ceramic capacitors made with Z5U material, they are not recommended.) 14 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Table 3. LM2594/LM2594HV Series Buck Regulator Design Procedure (Adjustable Output) (continued) PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable Output Voltage Version) 5. Catch Diode Selection (D1) A. The catch diode current rating must be at least 1.3 times greater than the maximum load current. Also, if the power supply design must withstand a continuous output short, the diode should have a current rating equal to the maximum current limit of the LM2594. The most stressful condition for this diode is an overload or shorted output condition. B. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. C. This diode must be fast (short reverse recovery time) and must be located close to the LM2594 using short leads and short printed circuit traces. Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best performance and efficiency, and should be the first choice, especially in low output voltage applications. Ultra-fast recovery, or High-Efficiency rectifiers are also a good choice, but some types with an abrupt turn-off characteristic may cause instability or EMl problems. Ultra-fast recovery diodes typically have reverse recovery times of 50 ns or less. Rectifiers such as the 1N4001 series are much too slow and should not be used. 5. Catch Diode Selection (D1) A. Refer to the table shown in Table 8. Schottky diodes provide the best performance, and in this example a 1A, 40V, 1N5819 Schottky diode would be a good choice. The 1A diode rating is more than adequate and will not be overstressed even for a shorted output. 6. Input Capacitor (CIN) A low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground to prevent large voltage transients from appearing at the input. In addition, the RMS current rating of the input capacitor should be selected to be at least 1/2 the DC load current. The capacitor manufacturers data sheet must be checked to assure that this current rating is not exceeded. The curve shown in Figure 25 shows typical RMS current ratings for several different aluminum electrolytic capacitor values. This capacitor should be located close to the IC using short leads and the voltage rating should be approximately 1.5 times the maximum input voltage. If solid tantalum input capacitors are used, it is recomended that they be surge current tested by the manufacturer. Use caution when using ceramic capacitors for input bypassing, because it may cause severe ringing at the VIN pin. For additional information, see EXTERNAL COMPONENTS section on input capacitors in Application Information section. 6. Input Capacitor (CIN) The important parameters for the Input capacitor are the input voltage rating and the RMS current rating. With a nominal input voltage of 28V, an aluminum electrolytic aluminum electrolytic capacitor with a voltage rating greater than 42V (1.5 x VIN) would be needed. Since the the next higher capacitor voltage rating is 50V, a 50V capacitor should be used. The capacitor voltage rating of (1.5 x VIN) is a conservative guideline, and can be modified somewhat if desired. The RMS current rating requirement for the input capacitor of a buck regulator is approximately 1/2 the DC load current. In this example, with a 400 mA load, a capacitor with a RMS current rating of at least 200 mA is needed. The curves shown in Figure 25 can be used to select an appropriate input capacitor. From the curves, locate the 50V line and note which capacitor values have RMS current ratings greater than 200 mA. A 47 F/50V low ESR electrolytic capacitor capacitor is needed. For a through hole design, a 47 F/50V electrolytic capacitor (Panasonic HFQ series or Nichicon PL series or equivalent) would be adequate. Other types or other manufacturers capacitors can be used provided the RMS ripple current ratings are adequate. For surface mount designs, solid tantalum capacitors are recommended. The TPS series available from AVX, and the 593D series from Sprague are both surge current tested. To further simplify the buck regulator design procedure, Texas Instruments is making available computer design software to be used with the Simple Switcher line to switching regulators. Switchers Made Simple (version 4.1 or later) is available from TI's web site, www.ti.com Table 4. Output Capacitor and Feedforward Capacitor Selection Table Output Voltage (V) Through Hole Output Capacitor Surface Mount Output Capacitor Panasonic Nichicon PL Feedforward AVX TPS Sprague Feedforward HFQ Series Series Capacitor Series 595D Series Capacitor (F/V) (F/V) (F/V) (F/V) 1.2 220/25 220/25 0 220/10 220/10 0 4 180/25 180/25 4.7 nF 100/10 120/10 4.7 nF 6 82/25 82/25 4.7 nF 100/10 120/10 4.7 nF 9 82/25 82/25 3.3 nF 100/16 100/16 3.3 nF 12 82/25 82/25 2.2 nF 100/16 100/16 2.2 nF Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 15 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Table 4. Output Capacitor and Feedforward Capacitor Selection Table (continued) Output Voltage (V) Through Hole Output Capacitor Surface Mount Output Capacitor Panasonic Nichicon PL Feedforward AVX TPS Sprague Feedforward HFQ Series Series Capacitor Series 595D Series Capacitor (F/V) (F/V) (F/V) (F/V) 15 82/25 82/25 1.5 nF 68/20 100/20 1.5 nF 24 82/50 120/50 1 nF 10/35 15/35 220 pF 28 82/50 120/50 820 pF 10/35 15/35 220 pF LM2594/LM2594HV Series Buck Regulator Design Procedure INDUCTOR VALUE SELECTION GUIDES (For Continuous Mode Operation) Figure 21. LM2594/LM2594HV-3.3 Figure 22. LM2594/LM2594HV-5.0 Figure 23. LM2594/LM2594HV-12 Figure 24. LM2594/LM2594HV-ADJ Table 5. Inductor Manufacturers Part Numbers Inductance (H) Current (A) Schott Renco Pulse Engineering Through Surface Through Surface Through Surface Hole Mount Hole Mount Hole Mount Coilcraft Surface Mount L1 220 0.18 67143910 67144280 RL-5470-3 RL1500-220 PE-53801 PE-53801-S DO1608-224 L2 150 0.21 67143920 67144290 RL-5470-4 RL1500-150 PE-53802 PE-53802-S DO1608-154 L3 100 0.26 67143930 67144300 RL-5470-5 RL1500-100 PE-53803 PE-53803-S DO1608-104 L4 68 0.32 67143940 67144310 RL-1284-68 RL1500-68 PE-53804 PE-53804-S DO1608-68 L5 47 0.37 67148310 67148420 RL-1284-47 RL1500-47 PE-53805 PE-53805-S DO1608-473 L6 33 0.44 67148320 67148430 RL-1284-33 RL1500-33 PE-53806 PE-53806-S DO1608-333 L7 22 0.60 67148330 67148440 RL-1284-22 RL1500-22 PE-53807 PE-53807-S DO1608-223 16 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Table 5. Inductor Manufacturers Part Numbers (continued) Inductance (H) Current (A) Schott Renco L8 330 0.26 67143950 67144320 RL-5470-2 RL1500-330 PE-53808 PE-53808-S DO3308-334 L9 220 0.32 67143960 67144330 RL-5470-3 RL1500-220 PE-53809 PE-53809-S DO3308-224 L10 150 0.39 67143970 67144340 RL-5470-4 RL1500-150 PE-53810 PE-53810-S DO3308-154 L11 100 0.48 67143980 67144350 RL-5470-5 RL1500-100 PE-53811 PE-53811-S DO3308-104 L12 68 0.58 67143990 67144360 RL-5470-6 RL1500-68 PE-53812 PE-53812-S DO1608-683 L13 47 0.70 67144000 67144380 RL-5470-7 RL1500-47 PE-53813 PE-53813-S DO3308-473 L14 33 0.83 67148340 67148450 RL-1284-33 RL1500-33 PE-53814 PE-53814-S DO1608-333 L15 22 0.99 67148350 67148460 RL-1284-22 RL1500-22 PE-53815 PE-53815-S DO1608-223 L16 15 1.24 67148360 67148470 RL-1284-15 RL1500-15 PE-53816 PE-53816-S DO1608-153 L17 330 0.42 67144030 67144410 RL-5471-1 RL1500-330 PE-53817 PE-53817-S DO3316-334 L18 220 0.55 67144040 67144420 RL-5471-2 RL1500-220 PE-53818 PE-53818-S DO3316-224 L19 150 0.66 67144050 67144430 RL-5471-3 RL1500-150 PE-53819 PE-53819-S DO3316-154 L20 100 0.82 67144060 67144440 RL-5471-4 RL1500-100 PE-53820 PE-53820-S DO3316-104 L21 68 0.99 67144070 67144450 RL-5471-5 RL1500-68 PE-53821 PE-53821-S DDO3316-683 L26 330 0.80 67144100 67144480 RL-5471-1 -- PE-53826 PE-53826-S -- L27 220 1.00 67144110 67144490 RL-5471-2 -- PE-53827 PE-53827-S -- Through Surface Hole Mount Through Pulse Engineering Surface Hole Through Mount Surface Hole Mount Coilcraft Surface Mount Table 6. Inductor Manufacturers Phone Numbers Coilcraft Inc. Phone (800) 322-2645 FAX (708) 639-1469 Phone +44 1236 730 595 FAX +44 1236 730 627 Phone (619) 674-8100 FAX (619) 674-8262 Pulse Engineering Inc., Phone +353 93 24 107 Europe FAX +353 93 24 459 Renco Electronics Inc. Phone (800) 645-5828 FAX (516) 586-5562 Phone (612) 475-1173 FAX (612) 475-1786 Coilcraft Inc., Europe Pulse Engineering Inc. Schott Corp. Table 7. Capacitor Manufacturers Phone Numbers Nichicon Corp. Panasonic AVX Corp. Sprague/Vishay Phone (708) 843-7500 FAX (708) 843-2798 Phone (714) 373-7857 FAX (714) 373-7102 Phone (803) 448-9411 FAX (803) 448-1943 Phone (207) 324-7223 FAX (207) 324-4140 Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 17 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Table 8. Diode Selection Table VR 1A Diodes Surface Mount Schottky Through Hole Ultra Fast Schottky Ultra Fast Recovery 20V MBRS130 30V Recovery All of these 1N5817 All of these diodes are SR102 diodes are rated to at 1N5818 rated to at least 60V. SR103 least 60V. 11DQ03 40V 50V or more MBRS140 MURS120 1N5819 MUR120 10BQ040 10BF10 SR104 HER101 10MQ040 11DQ04 11DF1 MBRS160 SR105 10BQ050 MBR150 10MQ060 11DQ05 MBRS1100 MBR160 10MQ090 SB160 SGL41-60 11DQ10 SS16 Block Diagram 18 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Application Information PIN FUNCTIONS +VIN --This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be present at this pin to minimize voltage transients and to supply the switching currents needed by the regulator. Ground --Circuit ground. Output --Internal switch. The voltage at this pin switches between (+VIN - VSAT) and approximately -0.5V, with a duty cycle of VOUT/VIN. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin should be kept to a minimum. Feedback --Senses the regulated output voltage to complete the feedback loop. ON /OFF --Allows the switching regulator circuit to be shut down using logic level signals thus dropping the total input supply current to approximately 80 A. Pulling this pin below a threshold voltage of approximately 1.3V turns the regulator on, and pulling this pin above 1.3V (up to a maximum of 25V) shuts the regulator down. If this shutdown feature is not needed, the ON /OFF pin can be wired to the ground pin or it can be left open, in either case the regulator will be in the ON condition. EXTERNAL COMPONENTS CIN --A low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground pin. It must be located near the regulator using short leads. This capacitor prevents large voltage transients from appearing at the input, and provides the instantaneous current needed each time the switch turns on. The important parameters for the Input capacitor are the voltage rating and the RMS current rating. Because of the relatively high RMS currents flowing in a buck regulator's input capacitor, this capacitor should be chosen for its RMS current rating rather than its capacitance or voltage ratings, although the capacitance value and voltage rating are directly related to the RMS current rating. The RMS current rating of a capacitor could be viewed as a capacitor's power rating. The RMS current flowing through the capacitors internal ESR produces power which causes the internal temperature of the capacitor to rise. The RMS current rating of a capacitor is determined by the amount of current required to raise the internal temperature approximately 10C above an ambient temperature of 105C. The ability of the capacitor to dissipate this heat to the surrounding air will determine the amount of current the capacitor can safely sustain. Capacitors that are physically large and have a large surface area will typically have higher RMS current ratings. For a given capacitor value, a higher voltage electrolytic capacitor will be physically larger than a lower voltage capacitor, and thus be able to dissipate more heat to the surrounding air, and therefore will have a higher RMS current rating. The consequences of operating an electrolytic capacitor above the RMS current rating is a shortened operating life. The higher temperature speeds up the evaporation of the capacitor's electrolyte, resulting in eventual failure. Selecting an input capacitor requires consulting the manufacturers data sheet for maximum allowable RMS ripple current. For a maximum ambient temperature of 40C, a general guideline would be to select a capacitor with a ripple current rating of approximately 50% of the DC load current. For ambient temperatures up to 70C, a current rating of 75% of the DC load current would be a good choice for a conservative design. The capacitor voltage rating must be at least 1.25 times greater than the maximum input voltage, and often a much higher voltage capacitor is needed to satisfy the RMS current requirements. A graph shown in Figure 25 shows the relationship between an electrolytic capacitor value, its voltage rating, and the RMS current it is rated for. These curves were obtained from the Nichicon "PL" series of low ESR, high reliability electrolytic capacitors designed for switching regulator applications. Other capacitor manufacturers offer similar types of capacitors, but always check the capacitor data sheet. "Standard" electrolytic capacitors typically have much higher ESR numbers, lower RMS current ratings and typically have a shorter operating lifetime. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 19 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Because of their small size and excellent performance, surface mount solid tantalum capacitors are often used for input bypassing, but several precautions must be observed. A small percentage of solid tantalum capacitors can short if the inrush current rating is exceeded. This can happen at turn on when the input voltage is suddenly applied, and of course, higher input voltages produce higher inrush currents. Several capacitor manufacturers do a 100% surge current testing on their products to minimize this potential problem. If high turn on currents are expected, it may be necessary to limit this current by adding either some resistance or inductance before the tantalum capacitor, or select a higher voltage capacitor. As with aluminum electrolytic capacitors, the RMS ripple current rating must be sized to the load current. Figure 25. RMS Current Ratings for Low ESR Electrolytic Capacitors (Typical) OUTPUT CAPACITOR COUT --An output capacitor is required to filter the output and provide regulator loop stability. Low impedance or low ESR Electrolytic or solid tantalum capacitors designed for switching regulator applications must be used. When selecting an output capacitor, the important capacitor parameters are; the 100 kHz Equivalent Series Resistance (ESR), the RMS ripple current rating, voltage rating, and capacitance value. For the output capacitor, the ESR value is the most important parameter. The output capacitor requires an ESR value that has an upper and lower limit. For low output ripple voltage, a low ESR value is needed. This value is determined by the maximum allowable output ripple voltage, typically 1% to 2% of the output voltage. But if the selected capacitor's ESR is extremely low, there is a possibility of an unstable feedback loop, resulting in an oscillation at the output. Using the capacitors listed in the tables, or similar types, will provide design solutions under all conditions. If very low output ripple voltage (less than 15 mV) is required, refer to the OUTPUT VOLTAGE RIPPLE AND TRANSIENTS section for a post ripple filter. An aluminum electrolytic capacitor's ESR value is related to the capacitance value and its voltage rating. In most cases, Higher voltage electrolytic capacitors have lower ESR values (see Figure 26 ). Often, capacitors with much higher voltage ratings may be needed to provide the low ESR values required for low output ripple voltage. The output capacitor for many different switcher designs often can be satisfied with only three or four different capacitor values and several different voltage ratings. See the quick design component selection tables in Figure 24 and Table 4 for typical capacitor values, voltage ratings, and manufacturers capacitor types. Electrolytic capacitors are not recommended for temperatures below -25C. The ESR rises dramatically at cold temperatures and typically rises 3X @ -25C and as much as 10X at -40C. See curve shown in Figure 27 . Solid tantalum capacitors have a much better ESR spec for cold temperatures and are recommended for temperatures below -25C. 20 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Figure 26. Capacitor ESR vs Capacitor Voltage Rating (Typical Low ESR Electrolytic Capacitor) CATCH DIODE Buck regulators require a diode to provide a return path for the inductor current when the switch turns off. This must be a fast diode and must be located close to the LM2594 using short leads and short printed circuit traces. Because of their very fast switching speed and low forward voltage drop, Schottky diodes provide the best performance, especially in low output voltage applications (5V and lower). Ultra-fast recovery, or High-Efficiency rectifiers are also a good choice, but some types with an abrupt turnoff characteristic may cause instability or EMI problems. Ultra-fast recovery diodes typically have reverse recovery times of 50 ns or less. Rectifiers such as the 1N4001 series are much too slow and should not be used. Figure 27. Capacitor ESR Change vs Temperature INDUCTOR SELECTION All switching regulators have two basic modes of operation; continuous and discontinuous. The difference between the two types relates to the inductor current, whether it is flowing continuously, or if it drops to zero for a period of time in the normal switching cycle. Each mode has distinctively different operating characteristics, which can affect the regulators performance and requirements. Most switcher designs will operate in the discontinuous mode when the load current is low. The LM2594 (or any of the Simple Switcher family) can be used for both continuous or discontinuous modes of operation. In many cases the preferred mode of operation is the continuous mode. It offers greater output power, lower peak switch, inductor and diode currents, and can have lower output ripple voltage. But it does require larger inductor values to keep the inductor current flowing continuously, especially at low output load currents and/or high input voltages. To simplify the inductor selection process, an inductor selection guide (nomograph) was designed (see Figure 21 through Figure 24 ). This guide assumes that the regulator is operating in the continuous mode, and selects an inductor that will allow a peak-to-peak inductor ripple current to be a certain percentage of the maximum design load current. This peak-to-peak inductor ripple current percentage is not fixed, but is allowed to change as different design load currents are selected. (See Figure 28.) Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 21 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Figure 28. (IIND) Peak-to-Peak Inductor Ripple Current (as a Percentage of the Load Current) vs Load Current By allowing the percentage of inductor ripple current to increase for low load currents, the inductor value and size can be kept relatively low. When operating in the continuous mode, the inductor current waveform ranges from a triangular to a sawtooth type of waveform (depending on the input voltage), with the average value of this current waveform equal to the DC output load current. Inductors are available in different styles such as pot core, toroid, E-core, bobbin core, etc., as well as different core materials, such as ferrites and powdered iron. The least expensive, the bobbin, rod or stick core, consists of wire wrapped on a ferrite bobbin. This type of construction makes for a inexpensive inductor, but since the magnetic flux is not completely contained within the core, it generates more Electro-Magnetic Interference (EMl). This magnetic flux can induce voltages into nearby printed circuit traces, thus causing problems with both the switching regulator operation and nearby sensitive circuitry, and can give incorrect scope readings because of induced voltages in the scope probe. Also see OPEN CORE INDUCTORS section. The inductors listed in the selection chart include ferrite E-core construction for Schott, ferrite bobbin core for Renco and Coilcraft, and powdered iron toroid for Pulse Engineering. Exceeding an inductor's maximum current rating may cause the inductor to overheat because of the copper wire losses, or the core may saturate. If the inductor begins to saturate, the inductance decreases rapidly and the inductor begins to look mainly resistive (the DC resistance of the winding). This can cause the switch current to rise very rapidly and force the switch into a cycle-by-cycle current limit, thus reducing the DC output load current. This can also result in overheating of the inductor and/or the LM2594. Different inductor types have different saturation characteristics, and this should be kept in mind when selecting an inductor. The inductor manufacturers data sheets include current and energy limits to avoid inductor saturation. DISCONTINUOUS MODE OPERATION The selection guide chooses inductor values suitable for continuous mode operation, but for low current applications and/or high input voltages, a discontinuous mode design may be a better choice. It would use an inductor that would be physically smaller, and would need only one half to one third the inductance value needed for a continuous mode design. The peak switch and inductor currents will be higher in a discontinuous design, but at these low load currents (200 mA and below), the maximum switch current will still be less than the switch current limit. Discontinuous operation can have voltage waveforms that are considerable different than a continuous design. The output pin (switch) waveform can have some damped sinusoidal ringing present. (See Figure 17 titled; Discontinuous Mode Switching Waveforms) This ringing is normal for discontinuous operation, and is not caused by feedback loop instabilities. In discontinuous operation, there is a period of time where neither the switch or the diode are conducting, and the inductor current has dropped to zero. During this time, a small amount of energy can circulate between the inductor and the switch/diode parasitic capacitance causing this characteristic ringing. Normally this ringing is not a problem, unless the amplitude becomes great enough to exceed the input voltage, and even then, there is very little energy present to cause damage. 22 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Different inductor types and/or core materials produce different amounts of this characteristic ringing. Ferrite core inductors have very little core loss and therefore produce the most ringing. The higher core loss of powdered iron inductors produce less ringing. If desired, a series RC could be placed in parallel with the inductor to dampen the ringing. The computer aided design software Switchers Made Simple (version 4.1) will provide all component values for continuous and discontinuous modes of operation. Figure 29. Post Ripple Filter Waveform OUTPUT VOLTAGE RIPPLE AND TRANSIENTS The output voltage of a switching power supply operating in the continuous mode will contain a sawtooth ripple voltage at the switcher frequency, and may also contain short voltage spikes at the peaks of the sawtooth waveform. The output ripple voltage is a function of the inductor sawtooth ripple current and the ESR of the output capacitor. A typical output ripple voltage can range from approximately 0.5% to 3% of the output voltage. To obtain low ripple voltage, the ESR of the output capacitor must be low, however, caution must be exercised when using extremely low ESR capacitors because they can affect the loop stability, resulting in oscillation problems. If very low output ripple voltage is needed (less than 15 mV), a post ripple filter is recommended. (See Figure 20.) The inductance required is typically between 1 H and 5 H, with low DC resistance, to maintain good load regulation. A low ESR output filter capacitor is also required to assure good dynamic load response and ripple reduction. The ESR of this capacitor may be as low as desired, because it is out of the regulator feedback loop. The photo shown in Figure 29 shows a typical output ripple voltage, with and without a post ripple filter. When observing output ripple with a scope, it is essential that a short, low inductance scope probe ground connection be used. Most scope probe manufacturers provide a special probe terminator which is soldered onto the regulator board, preferable at the output capacitor. This provides a very short scope ground thus eliminating the problems associated with the 3 inch ground lead normally provided with the probe, and provides a much cleaner and more accurate picture of the ripple voltage waveform. The voltage spikes are caused by the fast switching action of the output switch and the diode, and the parasitic inductance of the output filter capacitor, and its associated wiring. To minimize these voltage spikes, the output capacitor should be designed for switching regulator applications, and the lead lengths must be kept very short. Wiring inductance, stray capacitance, as well as the scope probe used to evaluate these transients, all contribute to the amplitude of these spikes. When a switching regulator is operating in the continuous mode, the inductor current waveform ranges from a triangular to a sawtooth type of waveform (depending on the input voltage). For a given input and output voltage, the peak-to-peak amplitude of this inductor current waveform remains constant. As the load current increases or decreases, the entire sawtooth current waveform also rises and falls. The average value (or the center) of this current waveform is equal to the DC load current. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 23 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com If the load current drops to a low enough level, the bottom of the sawtooth current waveform will reach zero, and the switcher will smoothly change from a continuous to a discontinuous mode of operation. Most switcher designs (irregardless how large the inductor value is) will be forced to run discontinuous if the output is lightly loaded. This is a perfectly acceptable mode of operation. Figure 30. Peak-to-Peak Inductor Ripple Current vs Load Current In a switching regulator design, knowing the value of the peak-to-peak inductor ripple current (IIND) can be useful for determining a number of other circuit parameters. Parameters such as, peak inductor or peak switch current, minimum load current before the circuit becomes discontinuous, output ripple voltage and output capacitor ESR can all be calculated from the peak-to-peak IIND. When the inductor nomographs shown in Figure 21 through Figure 24 are used to select an inductor value, the peak-to-peak inductor ripple current can immediately be determined. The curve shown in Figure 30 shows the range of (IIND) that can be expected for different load currents. The curve also shows how the peak-to-peak inductor ripple current (IIND) changes as you go from the lower border to the upper border (for a given load current) within an inductance region. The upper border represents a higher input voltage, while the lower border represents a lower input voltage (see Inductor Selection Guides). These curves are only correct for continuous mode operation, and only if the inductor selection guides are used to select the inductor value Consider the following example: VOUT = 5V, maximum load current of 300 mA VIN = 15V, nominal, varying between 11V and 20V. The selection guide in Figure 22 shows that the vertical line for a 0.3A load current, and the horizontal line for the 15V input voltage intersect approximately midway between the upper and lower borders of the 150 H inductance region. A 150 H inductor will allow a peak-to-peak inductor current (IIND) to flow that will be a percentage of the maximum load current. Referring to Figure 30, follow the 0.3A line approximately midway into the inductance region, and read the peak-to-peak inductor ripple current (IIND) on the left hand axis (approximately 150 mA p-p). As the input voltage increases to 20V, it approaches the upper border of the inductance region, and the inductor ripple current increases. Referring to the curve in Figure 30, it can be seen that for a load current of 0.3A, the peak-to-peak inductor ripple current (IIND) is 150 mA with 15V in, and can range from 175 mA at the upper border (20V in) to 120 mA at the lower border (11V in). 24 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Once the IIND value is known, the following formulas can be used to calculate additional information about the switching regulator circuit. 1. Peak Inductor or peak switch current 2. Minimum load current before the circuit becomes discontinuous 3. Output Ripple Voltage - = (IIND)x(ESR of COUT) - = 0.150Ax0.240=36 mV p-p - or 4. ESR of COUT OPEN CORE INDUCTORS Another possible source of increased output ripple voltage or unstable operation is from an open core inductor. Ferrite bobbin or stick inductors have magnetic lines of flux flowing through the air from one end of the bobbin to the other end. These magnetic lines of flux will induce a voltage into any wire or PC board copper trace that comes within the inductor's magnetic field. The strength of the magnetic field, the orientation and location of the PC copper trace to the magnetic field, and the distance between the copper trace and the inductor, determine the amount of voltage generated in the copper trace. Another way of looking at this inductive coupling is to consider the PC board copper trace as one turn of a transformer (secondary) with the inductor winding as the primary. Many millivolts can be generated in a copper trace located near an open core inductor which can cause stability problems or high output ripple voltage problems. If unstable operation is seen, and an open core inductor is used, it's possible that the location of the inductor with respect to other PC traces may be the problem. To determine if this is the problem, temporarily raise the inductor away from the board by several inches and then check circuit operation. If the circuit now operates correctly, then the magnetic flux from the open core inductor is causing the problem. Substituting a closed core inductor such as a torroid or E-core will correct the problem, or re-arranging the PC layout may be necessary. Magnetic flux cutting the IC device ground trace, feedback trace, or the positive or negative traces of the output capacitor should be minimized. Sometimes, locating a trace directly beneath a bobbin in- ductor will provide good results, provided it is exactly in the center of the inductor (because the induced voltages cancel themselves out), but if it is off center one direction or the other, then problems could arise. If flux problems are present, even the direction of the inductor winding can make a difference in some circuits. This discussion on open core inductors is not to frighten the user, but to alert the user on what kind of problems to watch out for when using them. Open core bobbin or "stick" inductors are an inexpensive, simple way of making a compact efficient inductor, and they are used by the millions in many different applications. THERMAL CONSIDERATIONS The LM2594/LM2594HV is available in two packages, an 8-pin through hole PDIP (P) and an 8-pin surface mount SOIC-8 (D). Both packages are molded plastic with a copper lead frame. When the package is soldered to the PC board, the copper and the board are the heat sink for the LM2594 and the other heat producing components. For best thermal performance, wide copper traces should be used and all ground and unused pins should be soldered to generous amounts of printed circuit board copper, such as a ground plane (one exception to this is the output (switch) pin, which should not have large areas of copper). Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air, and even double-sided or multilayer boards provide a better heat path to the surrounding air. Unless power levels are small, sockets are not recommended because of the added thermal resistance it adds and the resultant higher junction temperatures. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 25 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Package thermal resistance and junction temperature rise numbers are all approximate, and there are many factors that will affect the junction temperature. Some of these factors include board size, shape, thickness, position, location, and even board temperature. Other factors are, trace width, printed circuit copper area, copper thickness, single- or double-sided, multilayer board, and the amount of solder on the board. The effectiveness of the PC board to dissipate heat also depends on the size, quantity and spacing of other components on the board. Furthermore, some of these components such as the catch diode will add heat to the PC board and the heat can vary as the input voltage changes. For the inductor, depending on the physical size, type of core material and the DC resistance, it could either act as a heat sink taking heat away from the board, or it could add heat to the board. Circuit Data for Temperature Rise Curve (PDIP-8) Capacitors Through hole electrolytic Inductor Through hole, Schott, 100 H Diode Through hole, 1A 40V, Schottky PC board 4 square inches single sided 2 oz. copper (0.0028) Figure 31. Junction Temperature Rise, PDIP-8 Circuit Data for Temperature Rise Curve (Surface Mount) Capacitors Surface mount tantalum, molded "D" size Inductor Surface mount, Coilcraft DO33, 100 H Diode Surface mount, 1A 40V, Schottky PC board 4 square inches single sided 2 oz. copper (0.0028) Figure 32. Junction Temperature Rise, SOIC-8 26 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 The curves shown in Figure 31 and Figure 32 show the LM2594 junction temperature rise above ambient temperature with a 500 mA load for various input and output voltages. This data was taken with the circuit operating as a buck switcher with all components mounted on a PC board to simulate the junction temperature under actual operating conditions. This curve is typical, and can be used for a quick check on the maximum junction temperature for various conditions, but keep in mind that there are many factors that can affect the junction temperature. Figure 33. Delayed Startup Figure 34. Undervoltage Lockout for Buck Regulator DELAYED STARTUP The circuit in Figure 33 uses the the ON /OFF pin to provide a time delay between the time the input voltage is applied and the time the output voltage comes up (only the circuitry pertaining to the delayed start up is shown). As the input voltage rises, the charging of capacitor C1 pulls the ON /OFF pin high, keeping the regulator off. Once the input voltage reaches its final value and the capacitor stops charging, and resistor R2 pulls the ON /OFF pin low, thus allowing the circuit to start switching. Resistor R1 is included to limit the maximum voltage applied to the ON /OFF pin (maximum of 25V), reduces power supply noise sensitivity, and also limits the capacitor, C1, discharge current. When high input ripple voltage exists, avoid long delay time, because this ripple can be coupled into the ON /OFF pin and cause problems. This delayed startup feature is useful in situations where the input power source is limited in the amount of current it can deliver. It allows the input voltage to rise to a higher voltage before the regulator starts operating. Buck regulators require less input current at higher input voltages. UNDERVOLTAGE LOCKOUT Some applications require the regulator to remain off until the input voltage reaches a predetermined voltage. An undervoltage lockout feature applied to a buck regulator is shown in Figure 34, while Figure 35 and Figure 36 applies the same feature to an inverting circuit. The circuit in Figure 35 features a constant threshold voltage for turn on and turn off (zener voltage plus approximately one volt). If hysteresis is needed, the circuit in Figure 36 has a turn ON voltage which is different than the turn OFF voltage. The amount of hysteresis is approximately equal to the value of the output voltage. If zener voltages greater than 25V are used, an additional 47 k resistor is needed from the ON /OFF pin to the ground pin to stay within the 25V maximum limit of the ON /OFF pin. INVERTING REGULATOR The circuit in Figure 37 converts a positive input voltage to a negative output voltage with a common ground. The circuit operates by bootstrapping the regulators ground pin to the negative output voltage, then grounding the feedback pin, the regulator senses the inverted output voltage and regulates it. Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 27 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com This circuit has an ON/OFF threshold of approximately 13V. Figure 35. Undervoltage Lockout for Inverting Regulator This circuit has hysteresis Regulator starts switching at VIN = 13V Regulator stops switching at VIN = 8V Figure 36. Undervoltage Lockout with Hysteresis for Inverting Regulator CIN -- 68 F/25V Tant. Sprague 595D 120 F/35V Elec. Panasonic HFQ COUT -- 22 F/20V Tant. Sprague 595D 39 F/16V Elec. Panasonic HFQ Figure 37. Inverting -5V Regulator with Delayed Startup This example uses the LM2594-5 to generate a -5V output, but other output voltages are possible by selecting other output voltage versions, including the adjustable version. Since this regulator topology can produce an output voltage that is either greater than or less than the input voltage, the maximum output current greatly depends on both the input and output voltage. The curve shown in Figure 38 provides a guide as to the amount of output load current possible for the different input and output voltage conditions. The maximum voltage appearing across the regulator is the absolute sum of the input and output voltage, and this must be limited to a maximum of 40V. For example, when converting +20V to -12V, the regulator would see 32V between the input pin and ground pin. The LM2594 has a maximum input voltage spec of 40V (60V for the LM2594HV). 28 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Additional diodes are required in this regulator configuration. Diode D1 is used to isolate input voltage ripple or noise from coupling through the CIN capacitor to the output, under light or no load conditions. Also, this diode isolation changes the topology to closley resemble a buck configuration thus providing good closed loop stability. A Schottky diode is recommended for low input voltages, (because of its lower voltage drop) but for higher input voltages, a fast recovery diode could be used. Without diode D3, when the input voltage is first applied, the charging current of CIN can pull the output positive by several volts for a short period of time. Adding D3 prevents the output from going positive by more than a diode voltage. Figure 38. Inverting Regulator Typical Load Current Because of differences in the operation of the inverting regulator, the standard design procedure is not used to select the inductor value. In the majority of designs, a 100 H, 1A inductor is the best choice. Capacitor selection can also be narrowed down to just a few values. Using the values shown in Figure 37 will provide good results in the majority of inverting designs. This type of inverting regulator can require relatively large amounts of input current when starting up, even with light loads. Input currents as high as the LM2594 current limit (approx 0.8A) are needed for at least 2 ms or more, until the output reaches its nominal output voltage. The actual time depends on the output voltage and the size of the output capacitor. Input power sources that are current limited or sources that can not deliver these currents without getting loaded down, may not work correctly. Because of the relatively high startup currents required by the inverting topology, the delayed startup feature (C1, R1 and R2) shown in Figure 37 is recommended. By delaying the regulator startup, the input capacitor is allowed to charge up to a higher voltage before the switcher begins operating. A portion of the high input current needed for startup is now supplied by the input capacitor (CIN). For severe start up conditions, the input capacitor can be made much larger than normal. INVERTING REGULATOR SHUTDOWN METHODS To use the ON /OFF pin in a standard buck configuration is simple, pull it below 1.3V (@25C, referenced to ground) to turn regulator ON, pull it above 1.3V to shut the regulator OFF. With the inverting configuration, some level shifting is required, because the ground pin of the regulator is no longer at ground, but is now setting at the negative output voltage level. Two different shutdown methods for inverting regulators are shown in Figure 39 and Figure 40. Figure 39. Inverting Regulator Ground Referenced Shutdown Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 29 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com Figure 40. Inverting Regulator Ground Referenced Shutdown using Opto Device Figure 41. TYPICAL SURFACE MOUNT PC BOARD LAYOUT, FIXED OUTPUT (2X SIZE) CIN -- 10 F, 35V, Solid Tantalum AVX, "TPS series" COUT -- 100 F, 10V Solid Tantalum AVX, "TPS series" D1 -- 1A, 40V Schottky Rectifier, surface mount L1 -- 100 H, L20, Coilcraft DO33 Figure 42. TYPICAL SURFACE MOUNT PC BOARD LAYOUT, ADJUSTABLE OUTPUT (2X SIZE) CIN -- 10 F, 35V, Solid Tantalum AVX, "TPS series" COUT -- 100 F, 10V Solid Tantalum AVX, "TPS series" D1 -- 1A, 40V Schottky Rectifier, surface mount L1 -- 100 H, L20, Coilcraft DO33 R1 -- 1 k, 1% R2 -- Use formula in Design Procedure CFF -- 30 See Table 4. Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV LM2594, LM2594HV www.ti.com SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV Submit Documentation Feedback 31 LM2594, LM2594HV SNVS118C - DECEMBER 1999 - REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision B (April 2013) to Revision C * 32 Page Changed layout of National Data Sheet to TI format .......................................................................................................... 31 Submit Documentation Feedback Copyright (c) 1999-2013, Texas Instruments Incorporated Product Folder Links: LM2594 LM2594HV PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (C) Device Marking (4/5) LM2594HVM-12 NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2594H M-12 LM2594HVM-12/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594H M-12 LM2594HVM-3.3 NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2594H M-3.3 LM2594HVM-3.3/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594H M-3.3 LM2594HVM-5.0 NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2594H M-5.0 LM2594HVM-5.0/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594H M-5.0 LM2594HVM-ADJ NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2594H M-ADJ LM2594HVM-ADJ/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594H M-ADJ LM2594HVMX-12/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594H M-12 LM2594HVMX-3.3 NRND SOIC D 8 2500 TBD Call TI Call TI -40 to 125 2594H M-3.3 LM2594HVMX-3.3/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594H M-3.3 LM2594HVMX-5.0 NRND SOIC D 8 2500 TBD Call TI Call TI -40 to 125 2594H M-5.0 LM2594HVMX-5.0/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594H M-5.0 LM2594HVMX-ADJ/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594H M-ADJ LM2594HVN-12/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2594HV N-12 P+ LM2594HVN-3.3/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2594HV N-3.3 P+ LM2594HVN-5.0/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2594HV N-5.0 P+ Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (C) Device Marking (4/5) LM2594HVN-ADJ/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2594HV N-ADJ P+ LM2594M-12 NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2594 M-12 LM2594M-12/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594 M-12 LM2594M-3.3 NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2594 M-3.3 LM2594M-3.3/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594 M-3.3 LM2594M-5.0 NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2594 M-5.0 LM2594M-5.0/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594 M-5.0 LM2594M-ADJ/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594 M-ADJ LM2594MX-12/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 2594 M-12 LM2594MX-3.3/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594 M-3.3 LM2594MX-5.0/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594 M-5.0 LM2594MX-ADJ NRND SOIC D 8 2500 TBD Call TI Call TI -40 to 125 2594 M-ADJ LM2594MX-ADJ/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2594 M-ADJ LM2594N-12 NRND PDIP P 8 40 TBD Call TI Call TI -40 to 125 LM2594N -12 P+ LM2594N-12/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN | Call TI Level-1-NA-UNLIM -40 to 125 LM2594N -12 P+ LM2594N-3.3/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN | Call TI Level-1-NA-UNLIM -40 to 125 LM2594N -3.3 P+ LM2594N-5.0 NRND PDIP P 8 40 TBD Call TI Call TI -40 to 125 LM2594N -5.0 P+ LM2594N-5.0/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2594N -5.0 P+ Addendum-Page 2 Samples PACKAGE OPTION ADDENDUM www.ti.com Orderable Device 1-Nov-2013 Status (1) LM2594N-ADJ/NOPB ACTIVE Package Type Package Pins Package Drawing Qty PDIP P 8 40 Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM Op Temp (C) Device Marking (4/5) -40 to 125 LM2594N -ADJ P+ (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. 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Addendum-Page 3 Samples PACKAGE MATERIALS INFORMATION www.ti.com 11-Oct-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM2594HVMX-12/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594HVMX-3.3 SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594HVMX-3.3/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594HVMX-5.0 SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594HVMX-5.0/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594HVMX-ADJ/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594MX-12/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594MX-3.3/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594MX-5.0/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594MX-ADJ SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2594MX-ADJ/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 11-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2594HVMX-12/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2594HVMX-3.3 SOIC D 8 2500 367.0 367.0 35.0 LM2594HVMX-3.3/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2594HVMX-5.0 SOIC D 8 2500 367.0 367.0 35.0 LM2594HVMX-5.0/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2594HVMX-ADJ/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2594MX-12/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2594MX-3.3/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2594MX-5.0/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2594MX-ADJ SOIC D 8 2500 367.0 367.0 35.0 LM2594MX-ADJ/NOPB SOIC D 8 2500 367.0 367.0 35.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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