Step-down DC/DC Conv er ter with Voltage Detector
R1221N Series
‘99.12.8
1
11
12
22
23
33
345
4545
45
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Rev. 1.11 - 1 -
n
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n OUTLINE
The R1221N Series are PWM step-down DC/DC Converter controllers embedded with a voltage detector, with
low supply current by CMOS process.
Each step-down DC/DC converter in these ICs consists of an oscillator, a PWM control circuit, a reference
voltage unit, an error amplifier, a soft-start circuit, a protection circuit, a PWM/VFM alternative circuit, a chip
enable circuit, and resistors for voltage detection. A low ripple, high efficiency step-down DC/DC converter can be
composed of this IC with only four external components, or a power-transistor, an inductor, a diode and a
capacitor.
The output voltage of DC/DC converter can be supervised by the built-in voltage detector.
With a PWM/VFM alternative circuit, when the load current is small, the operation turns into the VFM oscillator
from PWM oscillator automatically, therefore the efficiency at small load current is improved.
And the PWM/VFM alternative circuit is an option, in terms of C version and D version, the circuit is not included.
If the term of maximum duty cycle keeps on a certain time, the embedded protection circuit works. There are two
types of protection function. One is latch-type protection circuit, and it works to latch an external Power MOS with
keeping it disable. To release the condition of protection, after disable this IC with a chip enable circuit, enable it
again, or restart this IC with power-on. The other is Reset-type protection circuit, and it works to restart the
operation with soft-start and repeat this operation until maximum duty cy cle condition is released. Either of these
protection circuits can be designated by users’ request.
n
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n FEATURES
l Wide Range of Input Voltage · · · · · · · · · · · · · 2.3V to 13.2V
l Built-in Soft-start Function and two choices of Protection Function(Latch-type or Reset-type)
l Two choices of Oscillator Frequency · · · · · · · · · · 300kHz, 500kHz
l High Efficiency · · · · · · · · · · · · · · · · · · · · · · TYP. 90%
l Standby Current · · · · · · · · · · · · · · · · · · · · · TYP. 0µA
l Setting Output Voltage · · · · · · · · · · · · · · · · · Stepwise setting with a step of 0.1V in the range of
1.5V to 5.0V
l High Accuracy Output Voltage · · · · · · · · · · · · · · ±2.0%
l Setting Detector Threshold Voltage · · · · · · · · · · · Stepwise setting with a step of 0.1V in the range of
1.2V to 4.5V
l High Accuracy Detector Threshold Voltage· · · · · · · ±2.0%
l Low Temperature-Drift Coefficient of Output Voltage · TYP. ±100ppm/°C
n
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n APPLICATIONS
l Power source for hand-held communication equipment, cameras, video instruments such as VCRs,
camcorders.
l Power source for battery-powered equipment.
l Power source for household electrical appliances.
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Rev. 1.11 - 2 -
n BLOCK DIAGRAM
OSC
VIN
EXT
GND
VOUT
Vref
Vref
CE
Chip Enable
Soft Start
Protection
PWM/VFM
CONTROL
VDOUT
n SELECTION GUIDE
In the R1221N Series, the output voltage, the detector threshold, the oscillator frequency, the optional
function, and the taping type for the ICs can be selected at the user’s request.
The selection can be made by designating the part number as shown below;
R1221NXXXX-TR
- - -
a b c
Code Contents
a Setting Output Voltage(VOUT):
Stepwise setting with a step of 0.1V in the range of 1.5V to 5.0V is possible.
b Setting Detector Threshold(-VDET)
Stepwise setting with a step of 0.1V in the range of 1.2V to 4.5V is possible.
A:3.0V
c Designation of Oscillator Frequency and Optional Function
A:300kHz, with a PWM/VFM alternative circuit, Latch-type protection
B:500kHz, with a PWM/VFM alternative circuit, Latch-type protection
C:300kHz, without a PWM/VFM alternative circuit, Latch-type protection
D:500kHz, without a PWM/VFM alternative circuit, Latch-type protection
E:300kHz, with a PWM/VFM alternative circuit, Reset-type protection
F:500kHz, with a PWM/VFM alternative circuit, Reset-type protection
G:300kHz, without a PWM/VFM alternative circuit, Reset-type protection
H:500kHz, without a PWM/VFM alternative circuit, Reset-type protection
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Rev. 1.11 - 3 -
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n PIN CONFIGURATION
l SOT-23-6W
123
4
6
V
OUT GND CE
EXT VDOUT VIN
(mark side)
5
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n PIN DESCRIPTION
Pin No. Symbol Description
1 EXT External Transistor Drive Pin (Output Type ; CMOS)
2VD
OUT Voltage Detector Output Pin (Output Type ; Nch Open Drain )
3V
IN Power Supply Pin
4 CE Chip Enable Pin
5 GND Ground Pin
6V
OUT Pin for Monitoring Output Voltage
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n ABSOLUTE MAXIMUM RATING
Symbol Item Rating Unit
VIN V
IN Supply Voltage 15 V
VEXT EXT Pin Output Voltage -0.3~VIN+0.3 V
VCE CE Pin Input Voltage -0.3~VIN+0.3 V
VDOUT VDOUT Pin Output Voltage -0.3~15 V
VOUT V
OUT Pin Input Voltage -0.3~VIN+0.3 V
IEXT EXT Pin Inductor Drive Output Current ±25 mA
PD Power Dissipation 250 mW
Topt Operating Temperature Range -40~+85 °C
Tstg Storage Temperature Range -55~+125 °C
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Rev. 1.11 - 4 -
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n ELECTRICAL CHARACTERISTICS
lR1221N***A(C,E,G) Output Voltage : Vo, Detector Threshold : VD (Topt=25°C)
Symbol Item Conditions MIN. TYP. MAX. Note* Unit
VIN Operating Input Voltage 2.3 13.2 V
VOUT Step-down Output Voltage VIN=VCE=Vo+1.2V, IOUT=-10mA Vo´
0.98
Vo Vo´
1.02
AV
DVOUT/
DT
Step-down Output Voltage
Temperature Coefficient
-40°C £ Topt £ 85°C±100 ppm/
°C
fosc Oscillator Frequency VIN=VCE=Vo+1.2V, IOUT=-100mA 240 300 360 A kHz
DfOSC/
DT
Frequency Temperature
Coefficient
-40°C £ Topt £ 85°C±0.3 %/
°C
IDD1 Supply Current1 VIN=13.2V,VCE=13.2V,VOUT=13.2V 100 160 B mA
Istb Standby Current VIN=13.2V,VCE=0V,VOUT=0V 0 0.5 C mA
IEXTH EXT "H" Output Current VIN=8V,VEXT=7.9V,VOUT=8V,VCE=8V -10 -6 D mA
IEXTL EXT "L" Output Current VIN=8V,VEXT=0.1V,VOUT=0V,VCE=0V 10 20 D mA
ICEH CE "H" Input Current VIN=13.2V,VCE=13.2V,VOUT=13.2V 0 0.5 E mA
ICEL CE "L" Input Current VIN=13.2V,VCE=0V,VOUT=13.2V -0.5 0 E mA
VCEH CE "H" Input Voltage VIN=8V,VCE=0V®1.5V 0.8 1.2 F V
VCEL CE "L" Input Voltage VIN=8V,VCE=1.5V®0V 0.3 0.8 F V
Maxdty Oscillator Maximum Duty Cycle 100 %
VFMdty VFM Duty Cycle Applied to B and F versions only 25 %
Tstart Delay Time by Soft-Start
function
VIN=Vo+1.2V,VCE=0V®Vo+1.2V
At 80% of rising
5 1016Fms
Tprot Delay Time for protection circuit VIN=Vo+1.2V,VCE=Vo+1.2V®0V 135Gms
IVDLK VDOUT Output Leakage Current VIN=VOUT=VCE=VDOUT=8V 0 0.5 I mA
IVDL VDOUT “L” Output Current VIN=VOUT=2.3V, VCE=0V, VDOUT=0.1V 0.5 1 I mA
-VDET Detector Threshold VIN=6V, VCE=6V, VOUT=VD´1.2V®0V VD´
0.98
VDVD´
1.02
JV
tVDET Output Delay Time for Released
Voltage
VIN=6V, VCE=6V, VOUT=0V®VD´1.2V
At 80% of rising
2510Jms
VHYS Detector Threshold Hysteresis VIN=6V, VCE=6V, VOUT=0V®VD´1.2V VD´
0.01
VD´
0.03
VD´
0.05
JmV
D-VDET/
DT
Detector Threshold
Temperature Coefficient
-40°C £ Topt £ 85°C±100 ppm/
°C
Note: Refer to Test Circuits
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Rev. 1.11 - 5 -
lR1221N***B(D,F,H) Output Voltage : Vo, Detector Threshold : VD (Topt=25°C)
Symbol Item Conditions MIN. TYP. MAX. Note* Unit
VIN Operating Input Voltage 2.3 13.2 V
VOUT Step-down Output Voltage VIN=VCE=Vo+1.2V, IOUT=-10mA Vo´
0.98
Vo Vo´
1.02
AV
DVOUT/
DT
Step-down Output Voltage
Temperature Coefficient
-40°C £ Topt £ 85°C±100 ppm/
°C
fosc Oscillator Frequency VIN=VCE=Vo+1.2V, IOUT=-100mA 400 500 600 A kHz
DfOSC/
DT
Frequency Temperature
Coefficient
-40°C £ Topt £ 85°C±0.3 %/
°C
IDD1 Supply Current1 VIN=13.2V,VCE=13.2V,VOUT=13.2V 140 200 B mA
Istb Standby Current VIN=13.2V,VCE=0V,VOUT=0V 0 0.5 C mA
IEXTH EXT "H" Output Current VIN=8V,VEXT=7.9V,VOUT=8V,VCE=8V -10 -6 D mA
IEXTL EXT "L" Output Current VIN=8V,VEXT=0.1V,VOUT=0V,VCE=0V 10 20 D mA
ICEH CE "H" Input Current VIN=13.2V,VCE=13.2V,VOUT=13.2V 0 0.5 E mA
ICEL CE "L" Input Current VIN=13.2V,VCE=0V,VOUT=13.2V -0.5 0 E mA
VCEH CE "H" Input Voltage VIN=8V,VCE=0V®1.5V 0.8 1.2 F V
VCEL CE "L" Input Voltage VIN=8V,VCE=1.5V®0V 0.3 0.8 F V
Maxdty Oscillator Maximum Duty Cycle 100 %
VFMdty VFM Duty Cycle Applied to B and F versions only 25 %
Tstart Delay Time by Soft-Start
function
VIN=Vo+1.2V,VCE=0V®Vo+1.2V
At 80% of rising
3610Fms
Tprot Delay Time for protection circuit VIN=Vo+1.2V,VCE=Vo+1.2V®0V 124Gms
IVDLK VDOUT Output Leakage Current VIN=VOUT=VCE=VDOUT=8V 0 0.5 I mA
IVDL VDOUT “L” Output Current VIN=VOUT=2.3V,VCE=0V, VDOUT=0.1V 0.5 1 I mA
-VDET Detector Threshold VIN=6V, VCE=6V, VOUT=VD´1.2V®0V VD´
0.98
VDVD´
1.02
JV
tVDET Output Delay Time for Released
Voltage
VIN=6V, VCE=6V, VOUT=0V®VD´1.2V
At 80% of rising
1.5 3.5 6.0 J ms
VHYS Detector Threshold Hysteresis VIN=6V, VCE=6V, VOUT=0V®VD´1.2V VD´
0.01
VD´
0.03
VD´
0.05
JmV
D-VDET/
DT
Detector Threshold
Temperature Coefficient
-40°C £ Topt £ 85°C±100 ppm/
°C
Note: Refer to Test Circuits
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Rev. 1.11 - 6 -
n TEST CIRCUITS
Inductor L : 27mH(Sumida Electronic, CD104) Diode SD : RB491D (Rohm, Schottky type)
Capacitor CL: 47mF(Tantalum type) C
IN : 22mF(Tantalum type)
Power MOS PMOS : HAT1020R(Hitachi) Resistor R : 100kW
C)
+
--
+
-
A)
4
3 6
5
V
OSCILLOSCOPE
SD
L
CL
VIN
1
PMOS
CIN 2
+
-
+
-
F)
4
3 6
5
V
OSCILLOSCOPE
SD
L
CL
1
PMOS
VIN CIN
2
A3
4
6
5
1
VIN 2
3
4
6
5
1
G)
OSCILLOSCOPE
VIN VOUT
2
E)
A
3
4
6
5
1
VIN
2
A
3
4
6
5
1
D) VEXT
VIN VOUT
2
A
3
4
6
5
1
H)
VIN VOUT
2
A
I)
VDOUT
3
4
6
5
1
VIN
2
3
4
6
5
1
OSCILLOSCOPE
J)
VIN VOUT
2
R
+
-
B) A3
4
6
5
1
CIN 2
VIN
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Rev. 1.11 - 7 -
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n TYPICAL APPLICATIONS AND APPLICATION HINTS
Vcc
Reset/
CPU
EXT
VIN VOUT
GND VDOUT
CE SD1
L
COUT
CIN
PMOS
R1
CE CONTROL
PMOS: HAT1020R (Hitachi), Si3443DV (Siliconix) L : CD105(Sumida, 27mH)
SD1 : RB491D (Rohm) COUT
: 47mF(Tantalum Type)
C
IN :10
mF(Tantalum Type) R1 : 100kW
When you use these ICs, consider the following issues;
l As shown in the block diagram, a parasitic diode is formed in each terminal, each of these diodes is not formed
for load current, therefore do not use it in such a way. When you control the CE pin by another power supply,
do not make its "H" level more than the voltage level of VIN pin.
l Detector threshold hysteresis is set at 3 percent of detector threshold voltage. (Min. 1 percent, Max. 5 percent)
l Setting Detector threshold voltage range depends on Output voltage of DC/DC converter.
Release Voltage from Reset condition must not be more than Output voltage of DC/DC converter.
(Detector Threshold Voltage´1.07 < Output Voltage of DC/DC converter´0.98
l When the R1221NXXXX is on stand-by mode, the output voltage of VDOUT is GND level, therefore if the pull-up
resistor for VDOUT pin is pulled up another power supply, a certain amount of current is loading through the
resistor.
l The operation of Latch-type protection circuit is as follows;
When the maximum duty cycle continues longer than the delay time for protection circuit, (Refer to the Electrical
Characteristics) the protection circuit works to shut-down the external Power MOS with its latching operation.
Therefore when an input/output voltage difference is small, the protection circuit may work even at small load
current.
To release the protection state, after disable this IC with a chip enable circuit, enable it again, or restart this IC
with power-on. However, in the case of restarting this IC with power-on, after the power supply is turned off, if
a certain amount of charge remains in CIN, or some voltage is forced to VIN from CIN, this IC might not be
restarted even after power-on.
If rising transition speed of supply voltage is too slow, or the time which is required for VIN voltage to reach
Output Voltage of DC/DC converter is longer than soft-starting time plus delay time for protection circuit,
protection circuit works before VIN voltage reaches Output Voltage of DC/DC converter. To avoid this condition,
make this IC disable(CE=”L”) first, then force VIN voltage, and after VIN voltage becomes equal or more than
VOUT, make this IC enable(CE=“H”).
l Set external components as close as possible to the IC and minimize the connection between the components
and the IC. In particular, a capacitor should be connected to VOUT pin with the minimum connection. And make
sufficient grounding and reinforce supplying. A large switching current flows through the connection of power
supply, an inductor and the connection of VOUT. If the impedance of power supply line is high, the voltage level of
power supply of the IC fluctuates with the switching current. This may cause unstable operation of the IC.
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Rev. 1.11 - 8 -
l Use capacitors with a capacity of 22mF or more for VOUT Pin, and with good high frequency characteristics such
as tantalum capacitors. We recommend you to use capacitors with an allowable voltage which is at least twice as
much as setting output voltage. This is because there may be a case where a spike-shaped high voltage is
generated by an inductor when an external transistor is on and off.
l Choose an inductor that has sufficiently small D.C. resistance and large allowable current and is hard to reach
magnetic saturation. And if the value of inductance of an inductor is extremely small, the ILX may exceed the
absolute maximum rating at the maximum loading.
Use an inductor with appropriate inductance.
l Use a diode of a Schottky type with high switching speed, and also pay attention to its current capacity.
l Do not use this IC under the condition at VIN voltage less than minimum operating voltage.
P The performance of power source circuits using these ICs extremely depends upon the peripheral circuits.
Pay attention in the selection of the peripheral circuits. In particular, design the peripheral circuits in a way that
the values such as voltage, current, and power of each component, PCB patterns and the IC do not exceed their
respected rated values.
n OPERATION of step-down DC/DC converter and Output Current
The step-down DC/DC converter charges energy in the inductor when Lx transistor is ON, and discharges the energy
from the inductor when Lx transistor is OFF and controls with less energy loss, so that a lower output voltage than the
input voltage is obtained. The operation will be explained with reference to the following diagrams :
<Basic Circuit> <Current through L>
Step 1 : LxTr turns on and current IL(=i1) flows, and energy is charged into CL. At this moment, IL increases from
ILmin(=0) to reach ILmax in proportion to the on-time period(ton) of LXTr.
Step 2 : When LxTr turns off, Schottky diode(SD) turns on in order that L maintains IL at ILmax, and current IL(=i2)
flows.
Step 3 : IL decreases gradually and reaches ILmin after a time period of topen, and SD turns off, provided that
in the continuous mode, next cycle starts before IL becomes to 0 because toff time is not enough. In this
case, IL value is from this ILmin(>0).
In the case of PWM control system, the output voltage is maintained by controlling the on-time period(ton), sith the
oscillator frequency(fosc) being maintained constant.
l Discontinuous Conduction Mode and Continuous Conduction Mode
The maximum value(ILmax) and the minimum value(ILmin) of the current which flows through the inductor are the
same as those when LxTr is ON and when it is OFF.
The difference between ILmax and ILmin, which is represented by DI ;
DI =ILmax –ILmin =VOUT´topen/L=(VIN-VOUT)´ton/L×××Equation 1
wherein T=1/fosc=ton+toff
duty(%)=ton/T´100=ton´fosc´100
topen£toff
SD
L
CL
VOUT
IOUT
VIN Lx Tr
i1
i2
T=1/fosc toffton
ILmax
ILmin topen
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Rev. 1.11 - 9 -
In Equation 1, VOUT´topen/L and (VIN-VOUT)´ton/L are respectively show the change of the current at ON, and the
change of the current at OFF.
When the output current(IOUT) is relatively small, topen<toff as illustrated in the above diagram. In this case, the
energy is charged in the inductor during the time period of ton and is discharged in its entirely during the time period
of toff, therefore ILmin becomes to zero(ILmin=0). When Iout is gradually increased, eventually, topen becomes to
toff (topen = toff), and when IOUT is further increased, ILmin becomes larger than zero(ILmin>0). The former mode
is
referred to as the discontinuous mode and the latter mode is referred to as continuous mode.
In the continuous mode, when Equation 1 is solved for ton and assumed that the solution is tonc,
tonc =T´VIN/VOUT××× Equation 2
When ton<tonc, the mode is the discontinuous mode, and when ton = tonc, the mode is the continuous mode.
n OUTPUT CURRENT AND SELECTION OF EXTERNAL COMPONENTS
When LxTr is ON:
(Wherein, Ripple Current P-P value is described as IRP, ON resistance of LXTr is described as Rp the direct current
of the inductor is described as RL.)
V
IN=VOUT+(Rp +RL)´IOUT+L´IRP/ton ×××Equation 3
When LxTr is OFF:
L
´IRP/ toff =VF+VOUT+RL´IOUT ×××Equation 4
Put Equation 4 to Equation 3 and solve for ON duty, ton/(toff+ton)=DON,
D
ON=(VOUT+VF+RL´IOUT)/(VIN+VF-Rp´IOUT)×××Equation 5
Ripple Current is as follows;
I
RP=(VIN-VOUT-Rp´IOUT-RL´IOUT)´DON/f/L ¼Equation 6
wherein, peak current that flows through L, LxTr, and SD is as follows;
ILmax=I
OUT+IRP/2 ¼Equation 7
Consider ILmax, condition of input and output and select external components.
HThe above explanation is directed to the calculation in an ideal case in continuous mode.
n External Components
1. Inductor
Select an inductor that peak current does not exceed ILmax. If larger current than allowable current flows,
magnetic saturation occurs and make transform efficiency worse.
When the load current is same, the smaller value of L, the larger the ripple current.
Provided that the allowable current is large in that case and DC current is small, therefore, for large output current,
efficiency is better than using an inductor with a large value of L and vice versa,
2. Diode
Use a diode with low VF (Schottky type is recommended.) and high switching speed.
Reverse voltage rating should be more than VIN and current rating should be equal or more than ILmax.
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Rev. 1.11 - 10 -
3. Capacitor
As for CIN, use a capacitor with low ESR(Equivalent Series Resistance) and a capacity of at least 10mF for stable
operation.
COUT can reduce ripple of Output Voltage, therefore 47mF to 100mF tantalum type is recommended.
4. Lx Transistor
Pch Power MOS FET is required for this IC.
Its breakdown voltage between gate and source should be a few volt higher than Input Voltage.
In the case of Input Voltage is low, to turn on MOS FET completely, select a MOS FET with low threshold voltage.
If a large load current is necessary for your application and important, choose a MOS FET with low ON resistance
for good efficiency.
If a small load current is mainly necessary for your application, choose a MOS FET with low gate capacity for good
efficiency.
Maximum continuous drain current of MOS FET should be larger than peak current, ILmax.
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Rev. 1.11 - 11 -
n TYPICAL CHARACTERISTCS
1) Output Voltage vs. Output Current
3.200
3.220
3.240
3.260
3.280
3.300
3.320
3.340
3.360
3.380
3.400
1E-05 0.0001 0.001 0.01 0.1 1
Output Current IOUT(A)
Output Voltage VOUT(V)
12V
8V
4.5V
R1221N33AH L=27uH
1.480
1.485
1.490
1.495
1.500
1.505
1.510
1.515
1.520
1E-05 0.0001 0.001 0.01 0.1 1
Output Current IOUT(A)
Output Voltage VOUT(V)
13.2V
8V
5V
2.3V
R1221N15XH L=27uH
2) Efficiency vs. Output Current
R1221N33AA(VIN=4.5V)
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV R1221N33AA(VIN=12V)
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV
R1221N33AC(VIN=4.5V)
0
20
40
60
80
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV R1221N33AB(VIN=12V)
0
20
40
60
80
100
0.1 1 10 100 1000
Outp ut Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV
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Rev. 1.11 - 12 -
R1221N33AC(VIN=4.5V)
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV R1221N33AC(VIN=12V)
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV
R1221N50XA(VIN=6.0V)
0
20
40
60
80
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV R1221N50XA(VIN=12V)
0
20
40
60
80
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV
R1221N50XB(VIN=6.0V)
0
20
40
60
80
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV R1221N50XB(VIN=12V)
0
20
40
60
80
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV
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Rev. 1.11 - 13 -
R1221N50XC(VIN=6.0V)
0
20
40
60
80
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV R1221N50XC(VIN=12V)
0
20
40
60
80
100
0.1 1 10 100 1000
Output Current IOUT(mA)
Efficiency (%)
CD104-27uH
Si3443DV
3) Ripple Voltage vs. Output Current
R1221N33AA
0
20
40
60
80
100
120
140
160
180
200
1 10 100 1000
Output Current IOUT(mA)
Ripple Voltage Vrpp(mV)
VIN4.5V
VIN8V
VIN12V
L=27uH
C=47uF(Ta) R1221N50XA
0
20
40
60
80
100
120
140
160
180
200
1 10 100 1000
Output Current IOUT(mA)
Ripple Voltage Vrpp(mV)
VIN6V
VIN8V
VIN12V
L=27uH
C=47uF(Ta)
R1221N33AB
0
20
40
60
80
100
120
140
160
180
200
1 10 100 1000
Output Current IOUT(mA)
Ripple Voltage Vrpp(mV)
VIN4.5V
VIN8V
VIN12V
L=27uH
C=47uF(Ta) R1221N50XB
0
20
40
60
80
100
120
140
160
180
200
1 10 100 1000
Output Current IOUT(mA)
Ripple Voltage Vrpp(mV)
VIN6V
VIN8V
VIN12V
L=27uH
C=47uF(Ta)
12345
Rev. 1.11 - 14 -
R1221N33AC
0
20
40
60
80
100
120
140
160
180
200
1 10 100 1000
Output Current IOUT(mA)
Ripple Voltage Vrpp(mV)
VIN4.5V
VIN8V
VIN12V
L=27uH
C=47uF(Ta) R1221N50XC
0
20
40
60
80
100
120
140
160
180
200
1 10 100 1000
Output Current IOUT(mA)
Ripple Voltage Vrpp(mV)
VIN6V
VIN8V
VIN12V
L=27uH
C=47uF(Ta)
4) Oscillator Frequency vs. Input Voltage
R1221N15XB
0
100
200
300
400
500
600
0 5 10 15
Input Voltage VIN(V)
Oscillator Frequency
fosc(kHz)
L=27uH R1221N15XA
0
100
200
300
400
500
600
0 5 10 15
Input Voltage VIN(V)
Oscillator Frequency
fosc(kHz)
L=27uH
5) Output Voltage vs. Input Voltage
R1221N15XB
1.47
1.48
1.49
1.50
1.51
1.52
1.53
0 5 10 15
Input Volt ag e VIN(V)
Output Voltage Vout(V)
L=27uH R1221N15XA
1.47
1.48
1.49
1.50
1.51
1.52
1.53
0 5 10 15
Input Voltage VIN(V)
Output Voltage Vout(V)
L=27uH
12345
Rev. 1.11 - 15 -
R1221N33AB
3.24
3.26
3.28
3.30
3.32
3.34
3.36
0 5 10 15
Input Voltage VIN(V)
Output Voltage Vout(V)
L=27uH R1221N33AA
3.24
3.26
3.28
3.30
3.32
3.34
3.36
0 5 10 15
Input Voltage VIN(V)
Output Voltage Vout(V)
L=27uH
6) Output Voltage vs. Temperature
R1221N33AH
3.27
3.28
3.29
3.30
3.31
-50 0 50 100
Temperature Topt
Output Voltage VOUT(V)
L=27uH R1221N15XB
1.47
1.48
1.49
1.50
1.51
-50 0 50 100
Temperature Topt
Output Voltage VOUT(V)
L=27uH
7) Detector Threshold vs. Temperature
R1221N25XA(VD=2.0V)
1.97
1.98
1.99
2.00
2.01
-50 0 50 100
Temperature Topt
Detector Threshold
VDOUT(V)
VIN=6V R1221N15XB(VD=1.2V)
1.18
1.19
1.20
1.21
1.22
-50 0 50 100
Temper ature Topt
Detector Threshold VDOUT(V)
VIN=6V
(°C) (°C)
(°C) (°C)
12345
Rev. 1.11 - 16 -
R1221N33AB(VD=3.0V)
2.94
2.96
2.98
3.00
3.02
3.04
3.06
-50 0 50 100
Temperature Topt
Detector Threshold VDOUT(V)
VIN=6V
8) Oscillator Frequency vs. Temperature
R1221N33AB
400
450
500
550
600
-50 0 50 100
Temperature Topt
Oscillator Frequency
fosc(kHz)
L=27uH
VIN=4.5V R1221N25XA
240
260
280
300
320
340
360
-50 0 50 100
Temperature Topt
Oscillator Frequency fosc(kHz)
L=27uH
VIN=3.7V
9) Supply Current vs. Temperature
R1221N33AH
90
95
100
105
110
115
120
125
130
135
-50 0 50 100
Temperature Topt
Supply Current1(uA)
VIN15V
VIN13.2V
VIN8V
R1221N33AG
50
60
70
80
90
100
-50 0 50 100
Temperature Topt
Supply Current1(uA)
VIN15V
VIN13.2V
VIN8V
(°C)
(°C) (°C)
(°C) (°C)
12345
Rev. 1.11 - 17 -
10) Soft-start Time vs. Temperature
R1221N33AB
0
2
4
6
8
10
-50 0 50 100
Temperature Topt
Soft-start Time(msec)
L=27uH
VIN=4.5V R1221N25XA
2
4
6
8
10
12
-50 0 50 100
Temperature Topt
Soft-start Time (msec)
L=27uH
VIN=3.7V
11) Delay Time for Latch-type Protection vs. Temperature
R1221N33AB
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
-50 0 50 100
Temperature Topt
Delay Time for Latch-type
Protection(msec)
VIN=4.5V R1221N25XA
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
-50 0 50 100
Temperature Topt
Delay Time for Latch-type
Protection(msec)
VIN=3.7V
12) Delay Time for Reset-type Protection vs. Temperature
R1221N33AH
0
1
2
3
4
5
-50 0 50 100
Temperature Topt
Delay Time for Reset-type
Protection(msec)
VIN=4.5V R1221N33AG
0
1
2
3
4
5
-50 0 50 100
Temperature Topt
Delay Time for Reset-type
Protection(msec)
VIN=4.5V
(°C) (°C)
(°C) (°C)
(°C) (°C)
12345
Rev. 1.11 - 18 -
13) VD Output Delay Time vs. Temperature
R1221N33AB
0
1
2
3
4
5
6
-50 0 50 100
Temperature Topt
VD Output Delay Time (msec)
VIN=8.0V R1221N25XA
0
1
2
3
4
5
6
-50 0 50 100
Temperature Topt
VD Output Delay
Time(msec)
VIN=8.0V
14) EXT”H” Output Current vs. Temperature
R1221N33AB
0
2
4
6
8
10
12
14
16
-50 0 50 100
Temperature Topt
EXT"H" Output Current(mA)
15) EXT ”L” Output Current vs. Temperature
R1221N33AB
0
5
10
15
20
25
30
-50 0 50 100
Temperature Topt
EXT"L"Output Current(mA)
(°C) (°C)
(°C)
(°C)
12345
Rev. 1.11 - 19 -
16) VDOUT “L” Output Current vs. Temperature
R1221N33AD
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
-50 0 50 100
Temperature Topt
VDLC(mA)
17) Load Transient Response
R1221N33AA
2.4
2.5
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
0 0.0005 0.001
Time (sec)
Output Voltage VOUT(V)
Output Current
IOUT(mA)
500
0.1
VIN=5V
L=27uH R1221N33AA
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
3.6
0 0.05 0.1
Time (sec)
Output Voltage VOUT(V)
Output Current
IOUT(mA)
500
0.1
VIN=5V
L=27uH
R1221N33AB
2.4
2.5
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
0 0.0005 0.001
Time (sec)
Output Voltage VOUT(V)
Output Current IOUT(mA)
500
0.1
VIN=5V
L=27uH R1221N33AB
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
3.6
0 0.05 0.1
Time (sec)
Output Voltage VOUT(V)
Output Current IOUT(mA)
500
0.1
VIN=5V
L=27uH
(°C)
12345
Rev. 1.11 - 20 -
R1221N33AC
2.4
2.5
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
0 0.0005 0.001
Time (sec)
Output Voltage VOUT(V)
IOUT(mA)
500
0.1
VIN=5V
L=27uH R1221N33AC
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
3.6
0 0.05 0.1
Time (sec)
Output Voltage VOUT(V)
Output Current IOUT(mA)
500
0.1
VIN=5V
L=27uH
R1221N33AD
2.4
2.5
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
0 0.0005 0.001
Time (sec)
Output Voltage VOUT(V)
Out ut Cu e t
IOUT(mA)
500
0.1
VIN=5V
L=27uH R1221N33AD
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
3.6
0 0.05 0.1
Time (sec)
Output Voltage VOUT(V)
Output Current IOUT(mA)
500
0.1
VIN=5V
L=27uH
18) Turn-on Waveform
R1221N33AA(VIN=10V,IOUT=0mA)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
-0.01 0 0.01 0.02
Time (sec)
Output Voltage VOUT(V)
L=27uH
0
10
CE
Volta
g
e(V)
R1221N33AA(VIN=5V,IOUT=0mA)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
-0.01 0 0.01 0.02
Time (sec)
Output Voltage VOUT(V)
L=27uH
0
5
CE
Volta
g
e(V)
12345
Rev. 1.11 - 21 -
R1221N33AB(VIN=10V,IOUT=0mA)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
-0.01 0 0.01 0.02
Time (sec)
Output Voltage VOUT(V)
L=27uH
0
10
CE
Voltage(V)
R1221N33AB(VIN=5V,IOUT=0mA)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
-0.01 0 0.01 0.02
Time (sec)
Output Voltage VOUT(V)
L=27uH
0
5
CE
Voltage(V
)
R1221N33AA(VIN=10V,IOUT=100mA)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
-0.01 0 0.01 0.02
Time (sec)
Output Voltage VOUT(V)
L=27uH
0
10
CE
Volta
g
e(V)
R1221N33AA(VIN=5V,IOUT=100mA)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
-0.01 0 0.01 0.02
Time (sec)
Output Voltage VOUT(V)
L=27uH
0
5
CE
Voltage(V)
R1221N33AB(VIN=10V,IOUT=100mA)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
-0.01 0 0.01 0.02
Time (sec)
Output Voltage VOUT(V)
L=27uH
0
10
CE
Voltage(V)
R1221N33AB(VIN=5V,IOUT=100mA)
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
-0.01 0 0.01 0.02
Time (sec)
Output Voltage VOUT(V)
L=27uH
0
5
CE
Voltage(V)
