RS5RM RICOH Co.,Ltd., RS5RM Datasheet - Page 8

• Manufacturer Part Number: RS5RM
• Description: Pwm Step-up Dc/dc Converter With Voltage Regulator And Detector
• Manufacturer: RICOH Co.,Ltd.

8
RS5RM
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
paring Vref1 and the V
by PWM circuits (i.e., by controlling the step-up operation).
Output Voltage
Output Voltage
output voltage.
V
V
V
Vf
IN
DD
OUT
0
0
V
IN
IN
IN
: Input Voltage
: V
: V
: ON Voltage of Diode
100µF
–Vf<V
–Vf≥V
DD
OUT
FIG. A Diagram of RS5RM including external circuits
Set Voltage
DD
Set Voltage
DD
DD
100µH
0:
output voltage by error amplifier circuits and subjecting LxTr to on-time control
0:
L
X
OUT
8
L
X
pin, with above-mentioned the V
Tr
PWM
OSC
V
DD
6
FIG. B Output Voltage vs. Input Voltage characteristic
–
+
Vref1
DD
1
output voltage by Pch Tr by comparing Vref2 and
V
IN
SS
–Vf (V) is output as it is from V
Pch Tr
Vref2
+
–
V
Area A
DD
V
1.2V
DD
OUT
0
output voltage being subjected to a
5
0
22µF
Input Voltage (V)
V
OUT
V
V
DD
DD
DD
0+Vf
V
1µF
output voltage by com-
OUT
Area B
V
OUT
DD
10V
pin without