RS5RJ RICOH Co.,Ltd., RS5RJ Datasheet - Page 8

• Manufacturer Part Number: RS5RJ
• Description: Vfm Step-up Dc/dc Converter With Voltage Regulator And Detector
• Manufacturer: RICOH Co.,Ltd.

8
RS5RJ
1. V
V
2. V
step-down operation by a linear regulator. This step-down operation will now be explained with reference to FIG. A.
The step-down operation is an operation for regulating the V
the V
OPERATION
DD
(1) In the case of V
(2) In the case of V
A constant voltage is output from V
DD
OUT
output voltage is shown in Fig. B.
DD
In Area B, LxTr is maintained in an OFF state, so that V
step-up operation.
In Area A, this IC functions as Step-up DC/DC converter. The step-up operation will now be explained
with reference to FIG. A. The step-up operation is an operation for regulating the V
comparing Vref1 and the V
trol by VFM circuits (i.e., by controlling the step-up operation).
Output Voltage
Output Voltage
output voltage.
V
V
V
Vf
IN
DD
OUT
V
IN
0
100µF
0
: Input Voltage
: V
: V
: ON Voltage of Diode
IN
IN
–Vf≥V
–Vf <V
DD
OUT
100µH
Set Voltage
FIG. A Diagram of RS5RJ including external circuits
Set Voltage
DD
DD
L
X
0:
0:
DD
8
L
output voltage by error amplifier circuits and subjecting LxTr to on-time con-
X
Tr
OUT
OSC
VFM
pin, with above-mentioned the V
V
DD
6
–
+
Vref1
FIG. B Output Voltage vs. Input Voltage characteristic
1
V
SS
DD
Pch Tr
output voltage by Pch Tr by comparing Vref2 and
IN
Vref2
+
–
–Vf (V) is output as it is from V
V
5
Area A
DD
22µF
V
V
1.2V
DD
OUT
OUT
0
0
output voltage being subjected to a
Input Voltage (V)
V
1µF
DD
V
DD
V
OUT
0+Vf
V
OUT
Area B
DD
output voltage by
DD
10V
pin without