RP902
Compound power supply IC with VD
SERIES
NO.EA-196-080311
OUTLINE
RP902 Series are CMOS-based compound power supply IC with Voltage Detector (VD), Voltage Detector
(VD), PWM/VFM Auto-switching Step-down DC/DC Converter with synchronous rectifier (DD1), PWM
Step-down DC/DC Converter control type with synchronous rectifier (DD2) and PWM Step-up DC/DC Converter
control type (DD3).
PWM/VFM Auto-switching Step-down DC/DC Converter control type with synchronous rectifier (DD1) has the
adoption of the synchronous rectification method that the switching element is built- in. A highly effective step-up
DC/DC converter can be composed only of the coil and the capacitor as external parts. The PWM/VFM
auto-switching control method is for achieving highly effective at VFM mode.
PWM Step-down DC/DC Converter with synchronous rectifier (DD2) has the adoption of the synchronous
rectification method that the switching element is built- in. A highly effective step-up DC/DC converter can be
composed only of the coil and the capacitor as external parts.
PWM Step-up DC/DC Converter (DD3) has the asynchronous rectification method by NMOS switching
element built-in. The step-up DC/DC converter can be composed only of the diode, the coli, the capacitors and
resistances as external parts.
When a large output current is necessary, to control by the additional external NMOS is possible. When the
output voltage is necessary to cut when it is off, to control additional external PMOS is possible.
As the protection circuits, the current limit circuits of DD1 and DD2 for limiting peak current of Lx at each clock
cycle, and DD3 has the ratio limitation time function. This IC has also the built-in reset type protection function.
When the limited condition is continue in certain time, the reset-start function is operated. The built-in low voltage
detection circuit (UVLO) is operating for stopping the output to prevent the malfunction when a low voltage is
detected.
As the soft-start circuits, the time of DD1, DD2 and DD3 is fixed. And DD1 and DD2 have the start-up order
control function by the trimming.
DD1 and DD2 have the built-in feed-back resistance. The setting output voltage is fixed. It can set by the
trimming in 0.1V step. DD3 has the feed-back resistance in externally. The setting output voltage can set
between 5.0V and 11V.
Controlling the external pin, it is possible to changing the output voltage dramatically from 72.7% to 100%.
(The output voltage range is between 11V and 8.0V (72.7%) when the default output voltage is set to 11V by
the external feed-back)
To using the trimming options, it is also possible to changing the output voltage dramatically from 57.8% to 100%.
(The output voltage range is between 9V and 5.2V (57.8%) when the default output voltage is set to 9V by the
external feed-back)
The Voltage Detector is monitoring the input voltage; the output is Nch open drain output. Power-on reset delay
time is also included and it is possible to selected 50ms or 100ms by the trimming.
FEATURE
•Input
Voltage Range ············································· 4.5V~5.5V
•Package
································································ QFN0404-20
•External
components ············································ C
IN
=0.1µF, 10µF
·········································· C
OUT
=10µF, L=4.7µH（DD1）
·········································· C
OUT
=10µF, L=4.7µH(DD2)
·········································· C
OUT
=10µF*3, L=4.7µH(DD3)
1
RP902
PWM/VFM Auto-switching Step-down DC/DC Converter with synchronous rectifier (DD1)
•Output
voltage range ························The output voltage in the range of 1.2V to 2.5V can be set by trim.
•Output
Voltage accuracy···················±2.0%
•Oscillation
Frequency ·······················Typ.1.35MHz
•Internal
drive ON resistance ·············Typ. Pch-0.5Ω, Nch-0.25Ω
•Soft-start
function ······························Typ. 1ms is fixed.
(The turning-on order with DD2 can be set by the trim.)
•Lx
peak limit current function ············Typ.1.3A
•Output
current ···································Max.800mA
•Reset
type protection function ··········Typ.1ms
PWM Step-down DC/DC Converter with synchronous rectifier (DD2)
•Output
voltage range ························The output voltage in the range of 1.2V to 3.3V can be set by trim.
•Output
Voltage accuracy···················±2.0%
•Oscillation
Frequency ·······················Typ.1.35MHz
•Internal
drive ON resistance ·············Typ. Pch-0.5Ω, Nch-0.5Ω
•Soft-start
function ······························Typ. 1ms is fixed.
(The turning-on order with DD1 can be set by the trim.)
•Lx
peak limit current function ············Typ.1.0A
•Output
current ···································Max.500mA
•Reset
type protection function ··········Typ.1ms
PWM Step-up DC/DC Converter (DD3)
•Output
voltage range ························The output voltage in the range of 5.0V to 11V can be set
by the external resistances.
•Output
Voltage accuracy···················±2.0%
•Oscillation
Frequency ·······················Typ.1.35MHz
•Internal
drive ON resistance ·············Typ. Nch-0.4Ω
•Soft-start
function ······························Typ. 10ms is fixed.
•Ratio
limitation time function ·············Typ.75%
•Output
current ···································Max.300mA(When internal FET is used )
•Reset
type protection function ··········Typ.1.5ms
VD
•Voltage
Detector Threshold voltage range············ The voltage detector threshold voltage in the range of
3.0V to 5.0V can be set by trim.
•Delay
time for Release·········································· Typ.50ms or 100ms can be set by trim.
APPLICATION
•Power
source for digital home appliance such as DVD player.(both blue and red type LD)
•
Power source for DVD-ROM/R/RW(both blue and red type LD) of note PC and desktop PC.
2
RP902
BLOCK DIAGRAM
V
IN
DD1
Step-
Down
DC/DC
Converter
V
INP1
Lx1
V
OUT1
GNDP1
V
DOUT
VD
Reset
Detector
V
INP2
DD2
Step-
Down
DC/DC
Converter
Lx2
EN12
EN3
ON/OFF
Control
Circuit
V
OUT2
GNDP2
V
INP2
DD3
V
SEL3
Step-Up
DC/DC
Converter
Lx3
V
FB3
GND
GNDP3
STBY3
EXT3
COMP3
* V
DOUT
is Nch Open Drain Pin
3
RP902
REFERENCE CIRCUIT
V
IN
0.1μF
DD1
Step-
Down
DC/DC
Converter
V
INP1
10μF
Lx1 4.7μH
V
OUT1
10μF 800mA
V
OUT1
GNDP1
V
DOUT
VD
Reset
Detector
V
INP2
DD2
Step-
Down
DC/DC
Converter
Lx2 4.7μH
10μF
V
OUT2
V
OUT2
500mA
EN12
EN3
ON/OFF
Control
Circuit
GNDP2
V
INP2
DD3
Lx3
4.7μH
PMOS
VSEL3
Step-Up
DC/DC
Converter
V
OUT3
300mA
10μF
V
FB3
10μFx 2
GNDP3
STBY3
EXT3
COMP3
GND
* Please set EXT3 pin as OPEN when the external NMOS is not necessary to use.
* Please set Lx3 pin as OPEN when the external NMOS will be using.
* Please set STBY3 pin as OPEN when the external PMOS is not necessary to use.
4
RP902
SELECTION GUIDE
In the RP902 series, output voltage, function options, etc. can be selected at the with user's request.
The selection can be made with designating the part number as shown below.
RP902K xx xx xx – x x – E2
↑ ↑ ↑ ↑
a b c d
Code
a
b
c
d
↑↑
e f
↑
g
←
Part Number
Contents
Designation of Package Type
K: QFN0404-20
Designation of DCDC1 output voltage.
Designation is possible in the range from 1.2V to 2.5V with a step of 0.1V.
Designation of DCDC2 output voltage.
Designation is possible in the range from 1.2V to 3.3V with a step of 0.1V.
Designation of DET detecting voltage.
Designation is possible in the range from 3.0V to 5.0V with a step of 0.1V.
Designation of function options1.
VFM/PWM alternative
Return delay time of VD
100ms
50ms
100ms
50ms
DCDC1,2
Power Good function
(V
DOUT
pin)
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
A
B
C
D
VFM / PWM
VFM / PWM
PWM ONLY
PWM ONLY
e
Designation of function options2.
The start order
A
B
C
D
f
E
F
G
H
J
K
L
M
g
DCDC1→2
DCDC1→2
DCDC1→2
DCDC1→2
DCDC1→2
DCDC1→2
DCDC2→1
DCDC2→1
DCDC2→1
DCDC2→1
DCDC2→1
DCDC2→1
Dynamic changeability
100½72.7%
100½72.7%
100½57.8%
100½57.8%
100½55.6%
100½55.6%
100½72.7%
100½72.7%
100½57.8%
100½57.8%
100½55.6%
100½55.6%
Designation of the taping type: (-E2 is the standard.)
* As for V
IN
voltage,V
OUT1
voltage, and V
OUT2
voltage normally stand up,if Power Good function is “yes” , V
DOUT
will be changed from “L” to “Hi-Z” after return delay time.
5
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