PWM/VFM step-down DC/DC converter with Synchronous
Rectifier
R1230D Series
2001. Sep. 8
Rev. 1.12 - 1 -
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OUTLINE
The R1230D Series are PWM step-down DC/DC Converters with synchronous rectifier, low supply current by CMOS
process.
Each of these ICs consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a
soft-start circuit, protection circuits, a protection against miss operation under low voltage (UVLO), PWM/VFM
alternative circuit, a chip enable circuit, and a driver transistor. A low ripple, high efficiency step-down DC/DC
converter can be easily composed of this IC with only a few kinds of external components, or an inductor and
capacitors. (As for R1230D001C/D types, divider resistors are also necessary.) In terms of Output Voltage, it is fixed
internally in the R1230DXX1A/B types. While in the R1230D001C/D types, Output Voltage is adjustable with external
divider resistors.
PWM/VFM alternative circuit is active with Mode Pin of the R1230D Series. Thus, when the load current is small,
the operation can be switching into the VFM operation from PWM operation by the logic of MODE pin and the
efficiency at small load current can be improved. As protection circuits, Current Limit circuit which limits peak current
of Lx at each clock cycle, and Latch type protection circuit which works if the term of Over-current condition keeps on
a certain time in PWM mode exist. Latch-type protection circuit works to latch an internal driver 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 or make the supply voltage at UVLO detector threshold level or lower than UVLO.
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FEATURES
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Built-in Driver ON Resistance
P-channel 0.35
, N-channel 0.45
(at V
IN
=3V)
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Built-in Soft-start Function (TYP. 1.5ms), and Latch-type Protection Function (Delay Time; TYP. 1.5ms)
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Two choices of Oscillator Frequency
500kHz, 800kHz
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PWM/VFM alternative with MODE pin
PWM operation; MODE pin at "L",
VFM operation; MODE pin at "H"
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High Efficiency
TYP. 90%
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Output Voltage
Stepwise Setting with a step of 0.1V in the range of 1.2V
4.0V(XX1A/B Type)
or adjustable in the range of 0.8V to V
IN
(001C/D Type)
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High Accuracy Output Voltage
2.0%(XX1A/B Type)
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Package
SON8 (Max height 0.9mm, thin type)
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APPLICATIONS
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Power source for portable equipment.
Rev. 1.12 - 2 -
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BLOCK DIAGRAM
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R1230DXX1A/B
V
IN
Lx
AGND
V
OUT
OSC
Vref
CE
Chip Enable
Soft Start
Current Protection
PWM/VFM
CONTROL
OUTPUT
CONTROL
UVLO
Phase Compensation
"H" Active
MODE
PGND
V
DD
"L"= PWM
CE
"H"= VFM
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R1230D001C/D
V
IN
Lx
AGND
V
FB
OSC
Vref
CE
Chip Enable
Soft Start
Current Protection
PWM/VFM
CONTROL
OUTPUT
CONTROL
UVLO
Phase Compensation
"H" Active
MODE
PGND
V
DD
"L"= PWM "H"= VFM
Rev. 1.12 - 3 -
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SELECTION GUIDE
In the R1230D Series, the output voltage, the oscillator frequency, 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;
R1230DXXXX-XX
a
b
c
d
Code
Contents
a
Setting Output Voltage(V
OUT
):
Stepwise setting with a step of 0.1V in the range of 1.2V to 4.0V is possible for A/B version.
"00" is for Output Voltage Adjustable C/D version
b
1 : fixed
c
Designation of Optional Function
A : 500kHz, Fixed Output Voltage
B : 800 kHz, Fixed Output Voltage
C : 500kHz, Adjustable Output Voltage
D : 800kHz, Adjustable Output Voltage
d
Designation of Taping Type; Ex. :TR,TL(refer to Taping Specification)
"TR" is prescribed as a standard.
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PIN CONFIGURATION
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SON-8
*Attention : Tab suspension leads in the
parts have GND level. (They are connected to
the reverse side of this IC.) Do not connect to
other wires or land patterns.
Unit : mm
2.9
0.2
0.48TYP
3.0
0.2
2.8
0.2
8 5
1 4
0.9 M
A
X
.
0.1
0.1
M
0.3
0.1
0.65
0.13
0.05
(0.2)
(0.2)
*
*
Rev. 1.12 - 4 -
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PIN DESCRIPTION
Pin No.
Symbol
Description
1
V
IN
Voltage Supply Pin
2
PGND
Ground Pin
3
V
DD
Voltage Supply Pin
4
CE
Chip Enable Pin (active with "H")
5
V
OUT
/V
FB
Output/Feedback Pin
6
MODE
Mode changer Pin (PWM mode at "L", VFM mode at "H".)
7
AGND
Ground Pin
8
Lx
Lx Pin
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ABSOLUTE MAXIMUM RATINGS
(AGND=PGND=0V)
Symbol
Item
Rating
Unit
V
IN
V
IN
Supply Voltage
6.5
V
V
DD
V
DD
Pin Voltage
6.5
V
V
LX
Lx Pin Voltage
-0.3
V
IN
+0.3
V
V
CE
CE
Pin Input Voltage
-0.3
V
IN
+0.3
V
V
MODE
MODE
Pin Input Voltage
-0.3
V
IN
+0.3
V
V
FB
V
FB
Pin Input Voltage
-0.3
V
IN
+0.3
V
I
LX
L
X
Pin Output Current
-0.8
A
P
D
Power Dissipation
250
mW
Topt
Operating Temperature Range
-40
+85
C
Tstg
Storage Temperature Range
-55
+125
C
Rev. 1.12 - 5 -
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ELECTRICAL CHARACTERISTICS
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R1230D**1A/B
(Topt=25
C)
Symbol
Item
Conditions
MIN.
TYP.
MAX. Unit
V
IN
Operating Input Voltage
2.4
5.5
V
V
OUT
Step-down Output Voltage
V
IN
=V
CE
=V
SET
+1.5V, V
MODE
=0V,
I
OUT
=10mA
TYP.
0.980
V
SET
TYP.
1.020
V
V
OUT
/
T
Step-down Output Voltage
Temperature Coefficient
-40
C
Topt
85
C
150
ppm
/
C
fosc
Oscillator Frequency(xx1A)
V
IN
=V
CE
=V
SET
+1.5V
425
500
575
kHz
fosc
Oscillator Frequency(xx1B)
V
IN
=V
CE
=V
SET
+1.5V
680
800
920
kHz
I
DD
Supply Current(xx1A)
V
IN
=V
CE
=V
SET
+1.5V,
V
OUT
=V
MODE
=0V
230
300
A
I
DD
Supply Current(xx1B)
V
IN
=V
CE
=V
SET
+1.5V,
V
OUT
=V
MODE
=0V
250
350
A
I
stb
Standby Current
V
IN
=5.5V, V
CE
=V
OUT
=0V
0
5
A
R
ONP
ON Resistance of
Pch Transistor
V
IN
=5.0V
0.20
0.35
0.60
R
ONN
ON Resistance of
Nch Transistor
V
IN
=5.0V
0.20
0.45
0.70
I
LX
leak Lx Leakage Current
V
IN
=5.5V, V
CE
=0V, V
LX
=0V/5.5V
-0.1
0.0
0.1
A
I
VOUT
V
OUT
Leakage Current
V
IN
=5.5V, V
CE
=0V, V
LX
=0V/5.5V
-0.1
0.0
0.1
A
I
CE
CE Input Current
V
IN
=5.5V, V
MODE
=0V, V
CE
=5.5V/0V
-0.1
0.0
0.1
A
V
CEH
CE "H" Input Voltage
V
IN
=5.5V, V
OUT
=0V
1.5
V
V
CEL
CE "L" Input Voltage
V
IN
=2.4V, V
OUT
=0V
0.3
V
Maxdty
Oscillator Maximum Duty Cycle
V
MODE
=0V
100
%
V
LX
Lx Limit Voltage
V
MODE
= V
OUT
=0V, V
IN
=V
CE
=3.0V
V
IN
-0.15 V
IN
-0.35 V
IN
-
0.55
V
T
start
Delay Time by Soft-Start function
at no load, V
IN
=V
CE
=V
SET
+1.5V
0.5
1.5
2.5
ms
T
prot
Delay Time for protection circuit
V
IN
=V
CE
=V
SET
+1.5V, V
MODE
=0V
0.5
1.5
2.5
ms
V
UVLO1
UVLO Threshold Voltage
V
IN
=V
CE
=2.5V->1.5V, V
OUT
=0V
1.8
2.1
2.2
V
V
UVLO2
UVLO Released Voltage
V
IN
=V
CE
=1.5V->2.5V, V
OUT
=0V
1.9
2.2
2.3
V
I
MODE
MODE Pin Input Current
V
IN
=5.5V, V
CE
=0V, V
MODE
=5.5V/0V
-0.1
0.1
A
V
MODEH
MODE "H" Input Voltage
V
IN
=V
CE
=5.5V, V
OUT
=0V
1.5
V
V
MODEL
MODE "L" Input Voltage
V
IN
=V
CE
=2.4V, V
OUT
=0V
0.3
V
VFMdty VFM Duty Cycle
V
IN
=V
CE
= V
MODE
=2.4V, V
OUT
=0V
55
65
85
%
Rev. 1.12 - 6 -
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R1230D001C/D
(Topt=25
C)
Symbol
Item
Conditions
MIN.
TYP.
MAX. Unit
V
IN
Operating Input Voltage
2.4
5.5
V
V
FB
Feedback Voltage
V
IN
=V
CE
=V
SET
+1.5V, V
MODE
=0V,
I
OUT
=10mA
0.776
0.800
0.824
V
V
FB
/
T
Feedback Voltage
Temperature Coefficient
-40
C
Topt
85
C
150
ppm
/
C
fosc
Oscillator Frequency(xx1C)
V
IN
=V
CE
=V
SET
+1.5V
425
500
575
kHz
fosc
Oscillator Frequency(xx1D)
V
IN
=V
CE
=V
SET
+1.5V
680
800
920
kHz
I
DD
Supply Current(xx1C)
V
IN
=V
CE
=5.5V, V
FB
=V
MODE
=0V
230
300
A
I
DD
Supply Current(xx1D)
V
IN
=V
CE
=5.5V, V
FB
=V
MODE
=0V
250
350
A
I
stb
Standby Current
V
IN
=5.5V, V
CE
=V
FB
=0V
0
5
A
R
ONP
ON Resistance of
Pch Transistor
V
IN
=5.0V
0.20
0.35
0.60
R
ONN
ON Resistance of
Nch Transistor
V
IN
=5.0V
0.20
0.45
0.70
I
LX
leak Lx Leakage Current
V
IN
=5.5V, V
CE
=0V, V
LX
=0V/5.5V
-0.1
0.0
0.1
A
I
VFB
V
FB
Leakage Current
V
IN
=5.5V, V
CE
=0V, V
FB
=0V/5.5V
-0.1
0.0
0.1
A
I
CE
CE Input Current
V
IN
=5.5V, V
MODE
=0V, V
CE
=5.5V/0V
-0.1
0.0
0.1
A
V
CEH
CE "H" Input Voltage
V
IN
=5.5V, V
FB
=0V
1.5
V
V
CEL
CE "L" Input Voltage
V
IN
=2.4V, V
FB
=0V
0.3
V
Maxdty Oscillator Maximum Duty Cycle V
MODE
=0V
100
%
V
LX
Lx Limit Voltage
V
IN
=V
CE
=3.0V, V
MODE
=0V, V
FB
=0V
V
IN
-0.15
V
IN
-
0.35
V
IN
-
0.55
V
T
start
Delay Time by Soft-Start function
at no load, V
IN
=V
CE
=V
SET
+1.5V
0.5
1.5
2.5
ms
T
prot
Delay Time for protection circuit
V
IN
=V
CE
=3.6V, V
MODE
=0V
1.5
ms
V
UVLO1
UVLO Threshold Voltage
V
IN
=V
CE
=2.5V->1.5V, V
FB
=0V
1.8
2.1
2.2
V
V
UVLO2
UVLO Released Voltage
V
IN
=V
CE
=1.5V->2.5V, V
FB
=0V
1.9
2.2
2.3
V
I
MODE
MODE Pin Input Current
V
IN
=5.5V, V
MODE
=5.5V/0V, V
CE
=0V
-0.1
0.1
A
V
MODE
MODE "H" Input Voltage
V
IN
=V
CE
=5.5V, V
FB
=0V
1.5
V
V
MODEL
MODE "L" Input Voltage
V
IN
=V
CE
=2.4V, V
FB
=0V
0.3
V
VFMdty VFM Duty Cycle
V
IN
=V
CE
=V
MODE
=2.4V, V
FB
=0V
55
65
85
%
Rev. 1.12 - 7 -
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TEST CIRCUITS
V
IN
Lx
V
DD
CE
V
OUT
AGND
PGND MODE
A
OSCILLOSCOPE
V
IN
Lx
V
DD
CE
V
OUT
AGND
PGND MODE
Test Circuit for Input Current and Leakage Current
Test Circuit for Input Voltage and UVLO voltage
V
IN
Lx
V
DD
CE
V
OUT
AGND
PGND MODE
10uF
L
V
OUT
OSCILLOSCOPE
Test Circuit for Output Voltage, Oscillator Frequency, Soft-Starting Time
V
IN
Lx
V
DD
CE
V
OUT
AGND
PGND MODE
A
V
IN
Lx
V
DD
CE
V
OUT
AGND
PGND MODE
A
OSCILLOSCOPE
Test Circuit for Supply Current and Standby Current
Test Circuit for ON resistance of Lx, Limit Voltage, Delay
Time of Protection Circuit
The bypass capacitor between Power Supply and GND is Ceramic capacitor 10
F.
Rev. 1.12 - 8 -
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TYPICAL APPLICATION AND TECHNICAL NOTES
1) Fixed Output Voltage Type
C
IN
C
OUT
AGND
MODE
V
OUT
CE
V
DD
PGND
Lx
V
IN
LOAD
L
V
OUT
L : 10
H LQH3C100K54(Murata)
C
OUT
: 10
F ECSTOJX106R(Panasonic)
C
IN
: 10
F C3216JB0J106M(TDK)
2) Adjustable Output Voltage Type
Rb
Cb
C
IN
C
OUT
AGND
MODE
V
FB
CE
V
DD
PGND
L
X
V
IN
LOAD
R1
R2
L
V
OUT
L:
10
H LQH3C100K54 (Murata)
C
OUT
:
10
F ECSTOJX106R (Panasonic)
C
IN
:
10
F C3216JB0J106M (TDK)
Standard value of the sum of Divider Resistors, R1+R2 is as much as 100k
.
Cb value for phase compensation depends on values of L, C, and R1. Refer to the technical notes.
If a ceramic capacitor is used as an output capacitor, add 0.2
or more resistance to compensate the ESR of the
capacitor.
When you use these ICs, consider the following issues;
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Input same voltage into Power Supply pins, V
IN
and V
DD
. Set the same level as AGND and PGND.
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When you control the CE pin and MODE pin by another power supply, do not make its "H" level more than the
voltage level of V
IN
/
V
DD
pin.
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Set external components such as an inductor, C
IN
, C
OUT
as close as possible to the IC, in particular, minimize the
wiring to V
IN
pin and PGND pin.
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At stand by mode, (CE="L"), the Lx output is Hi-Z, or both P-channel transistor and N-channel transistor of Lx pin
turn off.
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Use an external capacitor C
OUT
with a capacity of 10
F or more, and with good high frequency characteristics
such as tantalum capacitors.
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At VFM mode, (MODE="H"), Latch protection circuit does not operate.
Rev. 1.12 - 9 -
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If the mode is switched over into PWM mode from VFM mode during the operation, change the mode at light load
current. If the load current us large, output voltage may decline.
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Reinforce
the
V
IN
, PGND, and V
OUT
lines sufficiently. Large switching current may flow in these lines. If the
impedance of V
IN
and PGND lines is too large, the internal voltage level in this IC may shift caused by the
switching current, and the operation might be unstable.
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.
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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 Circuits>
<Current through L>
L
CL
V
OUT
I
OUT
V
IN
Pch Tr
i1
i2
Nch Tr
T=1/fosc
toff
ton
ILmax
ILmin
topen
Step 1:
P-channel Tr. 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 P-channel Tr.
Step 2:
When P-channel Tr. turns off, Synchronous rectifier N-channel Tr. turns on in order that L maintains IL at
ILmax, and current IL (=i2) flows.
Step 3:
IL (=i2) decreases gradually and reaches IL=ILmin=0 after a time period of topen, and N-channel Tr. 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 increases from this ILmin(>0).
In the case of PWM control system, the output voltage is maintained by controlling the on-time period (ton), with the
oscillator frequency (fosc) being maintained constant.
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Discontinuous Conduction Mode and Continuous Conduction Mode
The maximum value (ILmax) and the minimum value (ILmin) of the current flowing through the inductor are the
same as those when P-channel Tr. turns on and off.
The difference between ILmax and ILmin, which is represented by
I;
I = ILmax ILmin = V
OUT
topen / L = (V
IN
-V
OUT
)
ton/L
Equation 1
Wherein T=1/fosc=ton+toff
duty (%)=ton/T
100=ton
fosc
100
topen
toff
In Equation 1, V
OUT
topen/L and (V
IN
-V
OUT
)
ton/L respectively show the change of the current at "ON", and the
change of the current at "OFF".
When the output current (I
OUT
) 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 I
OUT
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,
Rev. 1.12 - 10 -
tonc =T
V
IN
/V
OUT
Equation 2
When ton<tonc, the mode is the discontinuous mode, and when ton=tonc, the mode is the continuous mode.
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OUTPUT CURRENT AND SELECTION OF EXTERNAL COMPONENTS
When P-channel Tr. of Lx is ON:
(Wherein, Ripple Current P-P value is described as I
RP
, ON resistance of P-channel Tr. and N-channel Tr. of Lx are
respectively described as Ronp and Ronn, and the DC resistor of the inductor is described as R
L
.)
V
IN
=V
OUT
+(Ronp+R
L
)
I
OUT
+L
I
RP
/ton
Equation 3
When P-channel Tr. of Lx is "OFF"(N-channel Tr. is "ON"):
L
I
RP
/toff = R
L
I
OUT
+ V
OUT
+ Ronn
I
OUT
Equation 4
Put Equation 4 to Equation 3 and solve for ON duty of P-channel transistor, ton/(toff+ton)=D
ON
,
D
ON
=(V
OUT
-Ronn
I
OUT+
R
L
I
OUT
)/(V
IN
+ Ronn
I
OUT
-Ronp
I
OUT
)
Equation 5
Ripple Current is as follows;
I
RP
=(V
IN
-V
OUT
-Ronp
I
OUT
-R
L
I
OUT
)
D
ON
/fosc/L
...
Equation 6
wherein, peak current that flows through L, and Lx Tr. is as follows;
ILmax=I
OUT
+I
RP
/2
...
Equation 7
Consider ILmax, condition of input and output and select external components.
5
The above explanation is directed to the calculation in an ideal case in continuous mode.
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How to Adjust Output Voltage and about Phase Compensation
As for Adjustable Output type, feedback pin (V
FB
) voltage is controlled to maintain 0.8V.
Output Voltage, V
OUT
is as following equation;
V
OUT
: R1+R2=VFB: R2
V
OUT
=V
FB
(R1+R2)/R2
Thus, with changing the value of R1 and R2, output voltage can be set in the specified range.
In the DC/DC converter, with the load current and external components such as L and C, phase might be behind 180
degree. In this case, the phase margin of the system will be less and stability will be worse. To prevent this, phase
margin should be secured with proceeding the phase. A zero is formed with R1, R2, and Cb.
Fpole
1/2
LC
OUT
Fzero
1/(2
(R1+R2)
Cb)
Considering external components, LC, set the appropriate value of R1+R2 and Cb.
Rb is effective for reducing the noise on V
FB
, therefore, add Rb so that R1+Rb=30k
.
When the R1
30k
, additional Rb is not necessary, so it should be wired to V
FB
directly.
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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.
Supposed that the load current is at the same, the smaller value of L is used, the larger the ripple current is.
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. Capacitor
Rev. 1.12 - 11 -
As for C
IN
, use a capacitor with low ESR (Equivalent Series Resistance) Ceramic type of a capacity at least 10
F
for stable operation.
C
OUT
can reduce ripple of Output Voltage, therefore as much as 10
F tantalum type is recommended.
s
TIMING CHART
Internal Oscillator Waveform
Internal Operational
Amplifier Output
Internal Soft-start
Set Voltage
Lx Pin Output
Soft-start Time
Stable
Output
Short
Delay Time of Protection
Latched
CE pin Voltage
Output Short
The timing chart as shown above describes the waveforms starting from the IC is enabled with CE and latched with
protection. During the soft-start time, until the level is rising up to the internal soft-start set voltage, the duty cycle of Lx
is gradually wider and wider to prevent the over-shoot of the voltage. During the term, the output of amplifier is "H",
then after the output voltage reaches the set output voltage, they are balanced with the stable state. Herein, if the
output pin would be short circuit, the output of amplifier would become "H" again, and the condition would continue for
1.5ms (TYP.), latch circuit would work and the output of Lx would be latched with "OFF". (Output ="High-Z")
If the output short is released before the latch circuit works (within 1.5ms after output shorted), the output of amplifier
is balanced in the stable state again.
Once the IC is latched, to release the protection, input "L" with CE pin, or make the supply voltage at UVLO level or
less.
s
TYPICAL CHARACTERISTICS
1) Output Voltage vs. Output Current
1.7
1.72
1.74
1.76
1.78
1.8
1.82
1.84
1.86
1.88
1.9
1
10
100
1000
Output Current I
OUT
[mA]
Output Voltage V
OUT
[mA]
Vin=3.3V PWM
Vin=3.3V VFM
Vin=5.0V PWM
Vin=5.0V VFM
R1230D181A
Rev. 1.12 - 12 -
1.7
1.72
1.74
1.76
1.78
1.8
1.82
1.84
1.86
1.88
1.9
1
10
100
1000
Output Current I
OUT
[mA]
Output Voltage V
OUT
[V]
Vin=3.3V PWM
Vin=3.3V VFM
Vin=5.0V PWM
Vin=5.0V VFM
R1230D181B
2.4
2.45
2.5
2.55
2.6
1
10
100
1000
Output Current I
OUT
[mA]
Output Voltage V
OUT
[V]
Vin=3.3V PWM
Vin=3.3V VFM
Vin=5.0V PWM
Vin=5.0V VFM
R1230D251B
2) Efficiency vs. Output Current
0
10
20
30
40
50
60
70
80
90
100
1
10
100
1000
Output Current I
OUT
[mA]
Efficiency [%]
Vin=3.3V PWM
Vin=3.3V VFM
Vin=5.0V PWM
Vin=5.0V VFM
R1230D181A
0
10
20
30
40
50
60
70
80
90
100
1
10
100
1000
Output Current I
OUT
[mA]
Efficiency [%]
Vin=3.3V PWM
Vin=3.3V VFM
Vin=5.0V PWM
Vin=5.0V VFM
R1230D181B
Rev. 1.12 - 13 -
0
10
20
30
40
50
60
70
80
90
100
1
10
100
1000
Output Current I
OUT
[mA]
Efficiency
[%]
Vin=3.3V PWM
Vin=3.3V VFM
Vin=5.0V PWM
Vin=5.0V VFM
R1230D251B
3) Ripple Voltage vs. Output Current
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
-1.00E-06 0.00E+00 1.00E-06
2.00E-06
3.00E-06
4.00E-06
5.00E-06
6.00E-06
7.00E-06
8.00E-06
Time [sec]
Output Ripple Voltage
Vripple
[
V
]
V
IN
=5.0V I
OUT
=200mA
PWM Mode
R1230D181A
C
OUT
=10uF Tantalum Capacitor ESR=400mohm
0
10
20
30
40
50
60
70
80
0
50
100
150
200
250
300
350
400
450
500
Output Current I
OUT
[mA]
Output Ripple Voltage
Vripple[V]
V
IN
=5.0V
V
IN
=3.3V
R1230D181B
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
-1.00E-06 0.00E+00 1.00E-06
2.00E-06
3.00E-06
4.00E-06
5.00E-06
6.00E-06
7.00E-06
8.00E-06
Time [sec]
Output Ripple Voltage
Vripple[V]
V
IN
=5.0V I
OUT
=200mA
PWM Mode
R1230D181B
C
OUT
=10uF Ceramic Capacitor ESR=220mohm
C
OUT
=10
F Tantalum Capacitor ESR=400m
Rev. 1.12 - 14 -
4) Output Waveform
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
-4.00E-06
-3.00E-06
-2.00E-06
-1.00E-06
0.00E+00
1.00E-06
2.00E-06
3.00E-06
4.00E-06
Time[sec]
AC Output Voltage V
AC
[V]
V
IN
=5.0V I
OUT
=10mA
PWM Mode
R1230D181B
C
OUT
=10uF Tantalum Capacitor ESR=400mohm
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
-4.00E-06
-3.00E-06
-2.00E-06
-1.00E-06
0.00E+00
1.00E-06
2.00E-06
3.00E-06
4.00E-06
Time[sec]
AC Output Voltage V
AC
[V]
V
IN
=5.0V I
OUT
=100mA
PWM Mode
R1230D181B
C
OUT
=10uF Tantalum Capacitor ESR=400mohm
5) Output Voltage vs. Input Voltage
1.7
1.75
1.8
1.85
1.9
2
2.5
3
3.5
4
4.5
5
5.5
6
Input Voltage V
IN
[V]
Output Voltage V
OUT
[V]
PWM
VFM
R1230D181B I
OUT
=20mA
6) Output Voltage vs. Temperature
1.7
1.72
1.74
1.76
1.78
1.8
1.82
1.84
1.86
1.88
1.9
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
Output Voltage V
OUT
[V]
R1230D181B I
OUT
=100mA
(
C)
Rev. 1.12 - 15 -
0.7
0.75
0.8
0.85
0.9
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
Output Voltage V
OUT
[V]
R1230D001C/D I
OUT
=100mA
7) Oscillator Frequency vs. Temperature
300
400
500
600
700
800
900
1000
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
Frequency f
OSC
[kHz]
V
IN
=V
OUT
+1.5V
8) Supply Current vs. Temperature
100
170
240
310
380
450
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
Supply Current Iss[uA]
800kHz
500kHz
V
IN
=5.5V
9) Soft-start time vs. Temperature
0
0.6
1.2
1.8
2.4
3
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
Soft-start Time Tsoft[ms]
800kHz
500kHz
R1230D181B V
IN
=3.3V
(
C)
(
C)
(
C)
(
C)
Rev. 1.12 - 16 -
10) Delay Time for protection vs. Temperature
0
0.6
1.2
1.8
2.4
3
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
Delay Time for Protection
Circuit Tprc
[ms]
11) UVLO Threshold/Released Voltage vs. Temperature
1.8
1.85
1.9
1.95
2
2.05
2.1
2.15
2.2
2.25
2.3
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
V
DD
Voltage level[V]
UVLO Detector Threshold
UVLO Released Voltage
12) CE Pin Input Voltage vs. Temperature
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
CE Input Voltage V
CE
[V]
CEL
CEH
13) Mode Pin Input Voltage vs. Temperature
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
MODE Input Voltage
V
MODE
[V]
MODEL
MODEH
(
C)
(
C)
(
C)
(
C)
Rev. 1.12 - 17 -
14) Duty Cycle at VFM Mode vs. Temperature
50
55
60
65
70
75
80
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
Duty Cycle at VFM Mode[%]
15) Lx Transistor On Resistance vs. Temperature
0
0.25
0.5
0.75
1
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
ON Resistance Ron[Ohm]
Nch Tr. On Resistance
Pch Tr. On Resistance
V
IN
=3.0V
16) Limit Voltage vs. Temperature
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-60
-40
-20
0
20
40
60
80
100
Temperature Topt
Limit Voltage Vlimit
[V]
17) Load Transient Response
-4.00E-05
-2.00E-05
0.00E+00
2.00E-05
4.00E-05
6.00E-05
8.00E-05
1.00E-04
1.20E-04
1.40E-04
Time[sec]
Load Current
100mA/div
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
AC Output V
AC
[V]
I
OUT
=0A
I
OUT
=100mA
R1230D181B V
IN
=5.0V PWM
(
C)
(
C)
(
C)
Rev. 1.12 - 18 -
-4.00E-05
-2.00E-05
0.00E+00
2.00E-05
4.00E-05
6.00E-05
8.00E-05
1.00E-04
1.20E-04
1.40E-04
Time[sec]
Load Current
100mA/div
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
Output Voltage V
AC
[V]
I
OUT
=0A
R1230D181B V
IN
=5.0V PWM
I
OUT
=200mA
-4.00E-06
1.00E-06
6.00E-06
1.10E-05
1.60E-05
2.10E-05
2.60E-05
3.10E-05
3.60E-05
Time [sec]
Load Current 100mA/div
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
AC Output Voltage
V
AC
[V]
I
OUT
=0A
R1230D181B V
IN
=5.0V PWM
I
OUT
=100mA
-0.0002
-0.0001
0
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007
0.0008
Time [sec]
Load Current 100mA/div
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
AC Output Voltage
V
AC
[V]
I
OUT
=2mA
I
OUT
=100mA
R1230D181B V
IN
=5.0V PWM
-4.00E-06
1.00E-06
6.00E-06
1.10E-05
1.60E-05
2.10E-05
2.60E-05
3.10E-05
3.60E-05
Time[sec]
Load Current 100mA/div
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
AC Output Voltage V
AC
[V]
I
OUT
=0A
R1230D181B V
IN
=5.0V PWM
I
OUT
=200mA
Rev. 1.12 - 19 -
-0.0002
-0.0001
0
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007
0.0008
Time [sec]
Load Current
100mA/div
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
AC Output Voltage V
AC
[V]
I
OUT
=2mA
I
OUT
=200mA
R1230D181B V
IN
=5.0V PWM
18) Turn-on Waveform
-1
0
1
2
3
4
5
-0.0004
0
0.0004
0.0008
0.0012
0.0016
0.002
0.0024
0.0028
Time [sec]
Output Voltage V
OUT
[V]
-10
-8
-6
-4
-2
0
2
4
CE Input Voltage V
CE
[V]
CE
V
OUT
R1230D181B V
IN
=5.0V
PWM Mode I
OUT
=0A
-1
0
1
2
3
4
5
-0.0004
0
0.0004
0.0008
0.0012
0.0016
0.002
0.0024
0.0028
Time [sec]
Output Voltage V
OUT
[V]
-10
-8
-6
-4
-2
0
2
4
CE Input Voltage V
CE
[V]
CE
V
OUT
R1230D181B V
IN
=5.0V
PWM Mode
I
OUT
=50mA
-1
0
1
2
3
4
5
-0.0004
0
0.0004
0.0008
0.0012
0.0016
0.002
0.0024
0.0028
Time [sec]
Output Voltage V
OUT
[V]
-10
-8
-6
-4
-2
0
2
4
CE Input Voltage V
CE
[V]
CE
V
OUT
R1230D181B V
IN
=5.0V
PWM Mode
I
OUT
=200mA
Rev. 1.12 - 20 -
-1
0
1
2
3
4
5
-0.0004
0
0.0004
0.0008
0.0012
0.0016
0.002
0.0024
0.0028
Time [sec]
Output Voltage V
OUT
[V]
-10
-8
-6
-4
-2
0
2
4
CE Input Voltage V
CE
(V)
CE
V
OUT
R1230D181B V
IN
=5.0V
VFM Mode I
OUT
=0A
-1
0
1
2
3
4
5
-0.0004
0
0.0004
0.0008
0.0012
0.0016
0.002
0.0024
0.0028
Time [sec]
Output Voltage V
OUT
[V]
-10
-8
-6
-4
-2
0
2
4
CE Input Voltage V
CE
[V]
CE
V
OUT
R1230D181B V
IN
=5.0V
VFM Mode I
OUT
=50mA
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