MIC29150/29300/29500/29750
High-Current Low -Dropout Regulators
**See Thermal Design Section
Super βeta PNP is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2012
M9999-122012-B
General Description
The MIC29150/29300/29500/29750 are high current, high
accuracy, low-dropout voltage regulators. Using Micrel's
proprietary Super βeta PNP® process with a PNP pass
element, these regulators feature 350mV to 425mV (full
load) typical dropout voltag es and ver y low groun d curr ent.
Designed for high current loads, these devices also find
applicat ions in lo wer current, ex trem ely low dr opout-critical
systems, where their tiny dropout voltage and ground
current values are important attributes.
The MIC29150/29300/29500/29750 are fully protected
against ov erc urr ent f aults , rever sed inp ut po lar ity, rever sed
lead insertion, overtemperature operation, and positive
and negative transient voltage spikes. Five pin fixed
voltage vers ions f eature lo gic leve l ON/OF F contr ol and an
error flag which signals whenever the output falls out of
regulation. Flagged states include low input voltage
(dropout), output current limit, overtemperature shutdown,
and extremely high voltage s pik es on the input.
On the MIC29x x1 and MIC29x x2, the ENAB LE pin may be
tied to VIN if it is not required for ON/OFF control. The
MIC29150/29300/29500 are available in 3-pin and 5-pin
TO-220 and surface mount TO-263 (D2Pak) packages.
The MIC29750 7.5A regulators are available in 3-pin and
5-pin TO-247 packages. The 1.5A, adjustable output
MIC29152 is available in a 5-pin power D-Pak (TO-252)
package.
For applications with input voltage 6V or below, see
MIC37xxx LDOs.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• High current capability:
− MIC29150/29151/29152/29153.............................. 1.5A
− MIC29300/29301/29302/29303................................. 3A
− MIC29500/29501/29502/29503................................. 5A
− MIC29750/29751/29752 ......................................... 7.5A
• Low-dropout vo lta ge
• Low ground current
• Accurate 1% guaranteed tolerance
• Extremely fast transient response
• Reverse-battery and “Load Dump” protection
• Zero-current shutdown mode
(5-pin versions)
• Error flag signals output out-of-regulation
(5-pin versions)
• Also characterized for smaller loads with industry-
leading performance specifications
• Fixed voltage and adjustable versions
Applications
• Battery-powered equipment
• High-efficiency “Green” computer systems
• Automotive electronics
• High-eff ic ienc y line ar lower suppl ies
• High-eff ic ienc y lost-regulator for switching supply
_________________________________________________________________________________________________________________________
Typical Application **
Fixed Output Voltage Adjustable Output Voltage
(*See Minimum Load Current Section)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
2
M9999-122012-B
Ordering Information
Part Number Junction Temperature
Range(1) Voltage Current Package
Standard
RoHS Compliant(2)
MIC29150-3.3BT MIC29150-3.3WT
(2)
–40°C to +125°C 3.3 1.5A 3-Pin TO-220
MIC29150-3.3BU MIC29150-3.3WU
(2)
–40°C to +125°C 3.3 1.5A 3-Pin TO-263
MIC29150-5.0BT MIC29150-5.0WT
(2)
–40°C to +125°C 5 1.5A 3-Pin TO-220
MIC29150-5.0BU MIC29150-5.0WU
(2)
–40°C to +125°C 5 1.5A 3-Pin TO-263
MIC29150-12BT MIC29150-12WT
(2)
–40°C to +125°C 12 1.5A 3-Pin TO-220
MIC29150-12BU MIC29150-12WU
(2)
–40°C to +125°C 12 1.5A 3-Pin TO-263
MIC29151-3.3BT MIC29151-3.3WT
(2)
–40°C to +125°C 3.3 1.5A 5-Pin TO-220
MIC29151-3.3BU MIC29151-3.3WU
(2)
–40°C to +125°C 3.3 1.5A 5-Pin TO-263
MIC29151-5.0BT MIC29151-5.0WT
(2)
–40°C to +125°C 5 1.5A 5-Pin TO-220
MIC29151-5.0BU MIC29151-5.0WU
(2)
–40°C to +125°C 5 1.5A 5-Pin TO-263
MIC29151-12BT MIC29151-12WT
(2)
–40°C to +125°C 12 1.5A 5-Pin TO-220
MIC29151-12BU MIC29151-12WU
(2)
–40°C to +125°C 12 1.5A 5-Pin TO-263
MIC29152BT MIC29152WT
(2)
–40°C to +125°C Adjustable 1.5A 5-Pin TO-220
MIC29152BU MIC29152WU
(2)
–40°C to +125°C Adjustable 1.5A 5-Pi n TO-263
— MIC29152WD
(2)
–40°C to +125°C Adjustable 1.5A 5-Pi n TO-252
MIC29153BT
(3)
Contact Factory –40°C to +125°C Adjustable 1.5A 5-Pi n TO-220
MIC29153BU
(3)
Contact Factory –40°C to +125°C Adjustable 1.5A 5-Pin TO -263
MIC29300-3.3BT MIC29300-3.3WT
(2)
–40°C to +125°C 3.3 3.0A 3-Pin TO-220
MIC29300-3.3BU MIC29300-3.3WU
(2)
–40°C to +125°C 3.3 3.0A 3-Pin TO-263
MIC29300-5.0BT MIC29300-5.0WT
(2)
–40°C to +125°C 5 3.0A 3-Pin TO-220
MIC29300-5.0BU MIC29300-5.0WU
(2)
–40°C to +125°C 5 3.0A 3-Pin TO-263
MIC29300-12BT MIC29300-12WT
(2)
–40°C to +125°C 12 3.0A 3-Pin TO-220
MIC29300-12BU MIC29300-12WU
(2)
–40°C to +125°C 12 3.0A 3-Pin TO-263
MIC29301-3.3BT MIC29301-3.3WT
(2)
–40°C to +125°C 3.3 3.0A 5-Pin TO-220
MIC29301-3.3BU MIC29301-3.3WU
(2)
–40°C to +125°C 3.3 3.0A 5-Pin TO-263
MIC29301-5.0BT MIC29301-5.0WT
(2)
–40°C to +125°C 5 3.0A 5-Pin TO-220
MIC29301-5.0BU MIC29301-5.0WU
(2)
–40°C to +125°C 5 3.0A 5-Pin TO-263
MIC29301-12BT MIC29301-12WT
(2)
–40°C to +125°C 12 3.0A 5-Pin TO-220
MIC29301-12BU MIC29301-12WU
(2)
–40°C to +125°C 12 3.0A 5-Pin TO-263
MIC29302BT MIC29302WT
(2)
–40°C to +125°C Adjustable 3.0A 5-Pi n TO-220
MIC29302BU MIC29302WU
(2)
–40°C to +125°C Adjustable 3.0A 5-Pin TO-263
MIC29303BT MIC29303WT
(2)
–40°C to +125°C Adjustable 3.0A 5-Pi n TO-220
MIC29303BU MIC29303WU
(2)
–40°C to +125°C Adjustable 3.0A 5-Pi n TO-263
MIC29500-3.3BT MIC29500-3.3WT
(2)
–40°C to +125°C 3.3 5.0A 3-Pin TO-220
Notes:
1. Junction temperature.
2. RoHS compliant with ‘hi gh-m elti ng solder’ exempt i on.
3. Speci al Order; pleas e cont act factory for availabi l i ty.
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
3
M9999-122012-B
Ordering Information (Continued)
Part Number Junction Temperature
Range(1) Voltage Current Package
Standard
RoHS Compliant(2)
MIC29500-5.0BT MIC29500-5.0WT
(2)
–40°C to +125°C 5 5.0A 3-Pin TO-220
MIC29501-3.3BT MIC29501-3.3WT
(2)
–40°C to +125°C 3.3 5.0A 5-Pin TO-220
MIC29501-3.3BU MIC29501-3.3WU
(2)
–40°C to +125°C 3.3 5.0A 5-Pin TO-263
MIC29501-5.0BT MIC29501-5.0WT
(2)
–40°C to +125°C 5 5.0A 5-Pin TO-220
MIC29501-5.0BU MIC29501-5.0WU
(2)
–40°C to +125°C 5 5.0A 5-Pin TO-263
MIC29502BT MIC29502WT
(2)
–40°C to +125°C Adj. 5.0A 5-Pin TO-220
MIC29502BU MIC29502WU
(2)
–40°C to +125°C Adj. 5.0A 5-Pin TO-263
MIC29503BT MIC29503WT
(2)
–40°C to +125°C Adj. 5.0A 5-Pin TO-220
MIC29503BU MIC29503WU
(2)
–40°C to +125°C Adj. 5.0A 5-Pin TO-263
MIC29750-3.3BWT
(4)
Contact Factory
(4)
–40°C to +125°C 3.3 7.5A 3-Pin TO-247
MIC29750-5.0BWT
(4)
Contact Factory
(4)
–40°C to +125°C 5 7.5A 3-Pin TO-247
MIC29751-3.3BWT
(4)
Contact Factory
(4)
–40°C to +125°C 3.3 7.5A 5-Pin TO-247
MIC29751-5.0BWT
(4)
Contact Factory
(4)
–40°C to +125°C 5 7.5A 5-Pin TO-247
MIC29752BWT
(4)
MIC29752WWT
(2, 4)
–40°C to +125°C Adjustable 7.5A 5-Pin TO-247
Note:
4. Not recommended for desi gn.
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
4
M9999-122012-B
Pin Configuration
3-Pin TO-220 (T)
MIC29150/29300/29500
5-Pin TO-220 Fixed Voltage (T)
MIC29151/29301/29501/29751
5-Pin TO-220 Adjustable Voltage (T)
MIC29152/29302/29502
5-Pin TO-220 Adjustable wit h Flag (T)
MIC29153/29303/29503
3-Pin TO-247 (WT)
MIC29750
5-Pin TO-247 Fixed Voltage (WT)
MIC29751
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
5
M9999-122012-B
Pin Configuration (Continued)
5-Pin TO-247 Adjustable Voltage (WT)
MIC29752
3-Pin TO-263 (D2Pak) (UT)
MIC29150/29300
5-Pin TO-263 (D2Pak) Fixe d Voltage (U)
MIC29151/29301/29501
5-Pin TO-263 (D2Pak) Adjustable Voltage (U)
MIC29302/29502
5-Pin TO-263 (D2Pak) Adjustable with Flag (U)
MIC29153/29303/29503
5-Pin TO-252 (D-Pak) Adjustable Voltage (D)
MIC29152
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
6
M9999-122012-B
Pin Description
Pin Number
TO-220
TO-247
TO-263
Pin Name
1 INPUT: Supplies the current to the output power device.
2 GND: TAB is also connected internally to the IC’s ground on D-PAK.
3 OUTPUT: The regulator output voltage.
Pin Description
Pin Number
Fixed
TO-220
TO-247
TO-263
Pin Number
Adjustable
TO-220
TO-247
TO-252
TO-263
Pin Number
Adj. with Flag
TO-220
TO-247
TO-263
Pin Name
1 1 — ENABLE: CMOS compatible control input. Logic high = enable, logic low =
shutdown.
2 2 2 INPUT: Supplies the current to the output power device
3, TAB 3, TAB 3, TA B GND: TAB is also connected internally to the IC’s ground on D-PAK.
4 4 4 OUTPUT: The regulator output voltage
— 5 5 ADJUST: Adjustable regulator feedback input that connects to the resistor
voltage divider that is placed from OUTPUT to GND in order to set the output
voltage.
5 — 1 FLAG: Active low error flag output signal that indicat es an out put fault con dit ion
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
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M9999-122012-B
Absolute Maximum Ratings(1)
Input Supply Voltage (VIN)(1) ........................... –20V to +60V
Enable Input Voltage (VEN) ................................ –0.3V to VIN
Lead Temperature (soldering, 5sec.) ......................... 260°C
Power Dissip ati on ..................................... Internally Limited
Storage Temperature Range .................... –65°C to +150°C
ESD Rating ................................................................. Note 3
Operating Ratings(2)
Operating Junction Temperature .............. –40°C to +125°C
Maxim um Operating Inp ut Vol tag e ................................ 26V
Package Thermal Resistance
TO-220 (θJC) ......................................................... 2°C/W
TO-263 (θJC) ......................................................... 2°C/W
TO-247 (θJC) ..................................................... 1.5°C/W
TO-252 (θJC) ......................................................... 3°C/W
TO-252 (θJA) ...................................................... 56°C/W
Electrical Characteristics(4, 13)
VIN = VOUT + 1V; IOUT = 10mA; TJ = 25°C. Bold valu es ind ica t e –40°C ≤ TJ ≤ +125°C, unless noted.
Parameter Condition Min. Typ. Max. Units
Output Voltage IOUT = 10mA –1 1 %
10mA ≤ IOUT ≤ IFL, (VOUT + 1V) ≤ VIN ≤26V
(5)
–2 2
Line Regulation IOUT = 10mA, (VOUT + 1V) ≤ VIN ≤26V 0.06 0.5 %
Load Regulation VIN = VOUT + 1V, 10mA ≤ IOUT ≤ 1.5A
(5,9)
0.2 1 %
∆VO
∆T Output Voltage
(9)
Temperature Coefficient. 20 100 ppm/°C
Dropout Voltage
∆VOUT = −1%(6)
MIC29150
MIC29300
MIC29500
MIC29750
IOUT = 100mA
IOUT = 750mA
IOUT = 1.5A
IOUT = 100mA
IOUT = 1.5A
IOUT = 3A
IOUT = 250mA
IOUT = 2.5A
IOUT = 5A
IOUT = 250mA
IOUT = 4A
IOUT = 7.5A
80
220
350
80
250
370
125
250
370
80
270
425
200
600
175
600
250
600
200
750
mV
Notes:
1. Maximum positi ve supply voltage of 60V must be of limited duration (<100msec) and duty cycle (≤1%). The maximum continuous supply voltage is
26V. Exceeding the absolut e maxim um rating may damage the device.
2. The device is not guaranteed to functi on outside its operati ng rating.
3. Devices are ESD sensitive. Handling precautions recommended.
4. Specification for packaged product only.
5. Full l oad current (IFL) is defined as 1.5A for the MIC29150, 3A for the MIC29300, 5A for the MIC29500, and 7.5A for the MIC29750 families.
6. Dropout voltage is defi ned as the input-to-output differential when the output voltage drops to 99% of its normal value with VOUT + 1V applied to VIN.
7. VIN = VOUT (nominal) + 1V. For example, use VIN = 4.3V for a 3.3V regulator or use 6V for a 5V regulator. Employ pulse-testing procedures to pin
current.
8. Ground pin current is t he regulator quiescent c urrent. T he tot al current drawn from the source is the sum of the load current plus the ground pin
current.
9. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperat ure range.
10. Therm al regulat i on is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding l oad or line
regulation effect s. Specif icat i ons are for a200mA load pulse at VIN = 20V (a 4W pulse) f or T = 10ms.
11. Comparator thresholds are expressed in terms of a voltage differential at the Adjust termi nal below the nominal ref erence volt age meas ured at 6V
input. To express these threshol ds in terms of output voltage change, multi pl y by the error amplifier gai n = VOUT/VREF = (R1 + R2)/R2. For example,
at a programmed output voltage of 5V, the Error output is guaranteed to go low when the output drops by 95mV x 5V/1.240V = 384mV. Thresholds
remain constant as a percent of VOUT as VOUT is varied, with the dropout warning occurring at typically 5% below nominal, 7.7% guaranteed.
12. VEN ≤ 0.8V and VIN ≤ 26V, VOUT = 0.
13. When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to ground.
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
8
M9999-122012-B
Electrical Characteristics(4, 13) (Continued)
VIN = VOUT + 1V; IOUT = 10mA; TJ = 25°C. Bold valu es ind icat e –40°C ≤ TJ ≤ +125°C, unless noted.
Parameter
Condition
Min.
Typ.
Max.
Units
Ground Current
MIC29150
MIC29300
MIC29500
MIC29750
Note 8
IOUT = 750mA , VIN = VOUT + 1V
IOUT = 1.5A
IOUT = 1.5A, VIN = VOUT + 1V
IOUT = 3A
IOUT = 2.5A, VIN = VOUT + 1V
IOUT = 5A
IOUT = 4A, VIN = VOUT + 1V
IOUT = 7.5A
8
22
10
37
15
70
35
120
20
35
50
75
mA
IGRNDDOGround Pin
Current at Dropout
VIN = 0.5V less than specified V OUT × IOUT = 10mA
MIC29150
MIC29300
MIC29500
MIC29750
0.9
1.7
2.1
3.1
mA
Current Limit
MIC29150
MIC29300
MIC29500
MIC29750
VOUT = 0V
(7)
VOUT = 0V(7)
VOUT = 0V(7)
VOUT = 0V(7)
2.1
4.5
7.5
9.5
3.5
5.0
10.0
15
A
en, Output Noise Voltage
(10Hz to 100kHz )
IL = 100mA
CL = 10µF
CL = 33µF 400
260 µV (rms)
Ground Current in
Shutdown MIC29150/1/2/3 only
VEN = 0.4V 2
10
30 µA
Reference
−
MIC29xx2/MIC29xx3
Reference Voltage 1.228
1.215 1.240 1.252
1.265 V
Reference Voltage
1.203 1.277 V
Adjust Pin Bias Current 40 80
120 nA
Reference Voltage
Temperature Coefficient Note 10 20 ppm/°C
Adjust Pin Bias Current
Temperature Coefficient 0.1 nA/°C
Flag Output (Error Comparator)
−
MIC29xx1/29xx3
Output Leakage Current VOH = 26V 0.01 1.00
2.00 µA
Output Low Voltage Device set for 5V, VIN = 4.5V
IOL = 250µA 220
300
400 mV
Upper Threshold Voltage Device set for 5V (11) 40
25 60 mV
Lower Threshold Voltage Device set for 5V (11) 75 95
140 mV
Hysteresis Device set for 5V
(11)
15 mV
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
9
M9999-122012-B
Electrical Characteristics(4, 13) (Continued)
VIN = VOUT + 1V; IOUT = 10mA; TJ = 25°C. Bold v alu es indica te –40°C ≤ TJ ≤ +125°C, unless noted.
Parameter
Condition
Min.
Typ.
Max.
Units
ENABLE Input
−
MIC29xx1/MIC29xx2
Input Logic Volta ge
Low (OFF)
High (ON)
2.4
0.8 V
Enable Pin
Input Current
VEN = 26V 100 600
750 µA
VEN = 0.8V 0.7 2
4
Regulator Output
Current in Shutdown Note 12 10 500 µA
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
10
M9999-122012-B
Typical Characteris tics (MIC2915x)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
11
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Typical Characteristics (MIC2915x) (Continued)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
12
M9999-122012-B
Typical Characteris tics (MIC2930x)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
13
M9999-122012-B
Typical Characteristics (MIC2930x) (Continued)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
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M9999-122012-B
Typical Chara cteri s tics (MIC2950x)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
15
M9999-122012-B
Typical Characteristics (MIC2950x) (Continued)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
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M9999-122012-B
Typical Characteris tics
−
MIC2975x
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
17
M9999-122012-B
Typical Characteris tics
−
MIC2975x (Continued)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
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M9999-122012-B
Functional Diagram
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
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M9999-122012-B
Application Information
The MIC29150/29300/29500/29750 are high-
performance low-dropout voltage regulators suitable for
all moderate to high-current voltage regulator
applications. Their 350mV to 425mV typical dropout
voltage at full load make them especially valuable in
battery powered systems and as high efficiency noise
filters in “post-regulator” applications. Unlike older NPN-
pass transistor designs, where the minimum dropout
voltage is limited by the base-emitter voltage drop and
collector-em itter saturatio n voltag e, dropout p erf orm ance
of the PNP output of these devices is limited merely by
the low VCE satur at ion volta ge.
A trade-off for the low-dropout voltage is a var ying base
driver requirement. But Micrel’s Super ßeta PNP®
process reduces this drive requirement to merely 1% of
the load current.
The MIC29150/29300/29500/29750 family of regulators
are fully protected from damage due to fault conditions.
Current lim iting is provided. This limiting is linear; output
current under overload conditions is constant. Thermal
shutdown disables the device when the die temperature
exceeds the 125°C maximum safe operating
temperature. L ine trans ient protec ti on al lo ws d evic e (a nd
load) survival even when the input voltage spikes
between –20V and +60V. When the input voltage
exceeds approximately 32V, the over voltage sensor
disables the regulator. The output structure of these
regulators allows voltages in excess of the desired
output volta ge to be appl ied witho ut rever se cur rent flow.
MIC29xx1 and MIC29xx2 versions offer a logic level
ON/OFF control: when disa bled, the d evices draw ne arl y
zero current.
An additional feature of this regulator family is a common
pinout: a desi gn’s c urrent r equirem ent m ay change up or
down yet use the same board layout, as all of these
regulators have identical pinouts.
MIC29XXX
OUT V
OUT
IN
GND
V
IN
Figure 3. Linear Regulators Require Only
Two Capacitors for Operation
Thermal Design
Linear regulators are simple to use. The most
complicated design parameters to consider are thermal
characteristics. Thermal design requires the following
application-specific parameters:
• Maximum ambient temperature, TA
• Output Current, IOUT
• Output Volta ge, VOUT
• Input Voltage, VIN
First, we calculate the power dissipation of the regulator
from thes e numbers and the de vice par ameters f rom this
datasheet.
( )
OUTINOUTD V V1.01IP −=
Eq. 1
where the gro und cur rent is approxim ated by 1% of IOUT.
Then the h eat s ink ther m al resistanc e is determ ined wi th
Equation 2:
( )
CSJC
D
AJMAX
SA PTT θ+
θ−
−
=θ
Eq. 2
where TJMAX ≤ 125°C and θCS is between 0 and 2°C/W.
The heat sink may be significantly reduced in
applications where the minimum input voltage is known
and is large compared with the dropout voltage. Use a
series input resistor to drop excessive voltage and
distribute the heat between this resistor and the
regulator. The low-dropout properties of Micrel Super
ßeta PNP® regulat ors allo w very si gnificant red uctions in
regulator po wer dissipation and the associated h eat sink
without comprom is ing perf ormance. When this technique
is employed, a capacitor of at least 0.1µF is needed
directly between the input and regulator ground.
Please refer to Application Note 9 and Application Hint
17 for further details and examples on thermal design
and heat sink specification.
With no heat sink in the application, calculate the
junction temperature to determine the maximum power
dissipation that will be allowed before exceeding the
maximum junction temperature of the MIC29152. The
maximum power allowed can be calculated using the
thermal resistance (θJA) of the D-Pak adhering to the
following criteria for the PCB design: 2 oz. copper and
100mm2 copper area for the MIC29152.
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
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M9999-122012-B
For example, given an expected maximum ambient
temperature (TA) of 75°C with VIN = 3.3V, VOUT = 2.5V,
and IOUT = 1.5A, first calculate the expected PD using
Equation 3:
PD=(3.3V–2.5V)1.5A–(3.3V)(0.016A)=1.1472W
Eq. 3
Next, calc ualte th e junctio n tem per ature for the expected
power dissipation.
TJ=(θJA×PD)+TA=(56°C/W×1.1472W)+75°C
=139.24°C
Eq. 4
Now determine the maximum power dissipation allowed
that would not exceed the IC’s maximum junction
temperature (125°C) without the useof a heat sink by:
PD(MAX) = (TJ(MAX)–TA)/θJA
= (125°C–75°C)/(56°C/W) = 0.893W
Eq. 5
Capacitor Requirements
For stability and minimum output noise, a capacitor on
the regulator output is necessary. The value of this
capacitor is dependent upon the output current; lower
currents allow smaller capacitors. The
MIC29150/29300/29500/29750 regulators are stable
with the following minimum capacitor values at full load,
as noted in Table 1:
Device
Full Load Capacitor
MIC29150
10µF
MIC29300
10µF
MIC29500
10µF
MIC29750
22µF
Table 1. Minimum Capacitor Values at Full Load
This capacitor need not be an expensive low ESR type:
aluminum electrolytics are adequate. In fact, extremely
low ESR capacitors may contribute to instability.
Tantalum capacitors are recommended for systems
where fast load transient response is important.
Where the regulator is powered from a source with high
AC impedance, a 0.1µF capacitor connected between
Input and GND is recommended. This capacitor should
have good characteristics to above 250kHz.
Minimum Load Current
The MIC29150–29750 regulators are specified between
finite loads. If the output current is too small, leakage
currents dominate and the output voltage rises. The
following minimum load current swamps any expected
leakage cur rent across the operat ing tem perature range,
as shown in Table 2:
Device
Minimum Load
MIC29150
5mA
MIC29300
7mA
MIC29500
10mA
MIC29750
10mA
Table 2. Minimum Load Currents
Adjustable Regulator Design
The adjustable regulator versions, MIC29xx2 and
MIC29xx3, allow programming the output voltage
anywhere between 1.25V and the 25V. Two resistors are
used. The resistor values are calculated by Equation 6:
−×= 1
1.240
V
RR
OUT
2
1
Eq. 6
where VOUT is the desired output voltage. Figure 4 shows
component definition. Applications with widely varying
load currents may scale the resistors to draw the
minim um load cur rent requi red for proper operation (see
“Minimum Load Current” sub-section).
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
21
M9999-122012-B
R1
R2
VIN VOUT
MIC29152BT
22µF
10µF
Figure 4. Adjustable Regulator with Resistors
Error Flag
MIC29xx1 and M IC29xx 3 v ersions f eatur e an Error Flag,
which looks at the output voltage and signals an error
conditio n when t his volt age drops 5% bel ow its ex pect ed
value. The error flag is an open-collector output that
pulls low under fault conditions. It may sink 10mA. Low
output voltage signifies a number of possible problems,
including an overcurrent fault (the device is in current
limit) and low input voltage. The flag output is inoperative
during overtemperature shutdown conditions.
Enable Input
MIC29xx1 and MIC29xx2 versions feature an enable
(EN) input that allows ON/OFF control of the device.
Special design allows “zero” current drain when the
device is disabled—only microamperes of leakage
current flows. The EN input has TTL/CMOS compatible
thresholds for simple interfacing with logic, or may be
directly tied to ≤30V. Enabling the regulator requires
approximately 20µA of current.
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
23
M9999-122012-B
Package Information(1) (Continued)
5-Pin TO-263 (U)
3-Pin TO-263 (U)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
24
M9999-122012-B
Package Information(1) (Continued)
5-Pin TO-247 (WT)
3-Pin TO-247 (WT)
Micrel, Inc.
MIC29150/29300/29500/29750
December 2012
25
M9999-122012-B
Package Information(1) (Continued)
5-Pin TO-252 (D)
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