R1211D002B RICOH [RICOH electronics devices division], R1211D002B Datasheet - Page 12

• Manufacturer Part Number: R1211D002B
• Description: STEP-UP DC/DC CONTROLLER
• Manufacturer: RICOH [RICOH electronics devices division]

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TIMING CHART
<Soft-start Operation>
is input to OP AMP is also gradually rising. V
therefore, V
is at "L", and switching does not start.
operation starts. V
V
comparator.
R1211x
(Step1)
(Step2)
FB
R1211x002A/R1211x002C
R1211x002B/R1211x002D
The voltage level of SS is rising gradually by constant current circuit of the IC and a capacitor. V
When the voltage level of SS becomes the setting voltage with the ration of R1 and R2 or more, switching
. Duty cycle depends on the lowest level among AMPOUT, SS, and DTC of the 4 input terminals in the PWM
Soft-start operation is starting from power-on as follows:
FB
voltage is rising up to the setting voltage with input voltage and the ration of R1 and R2. AMPOUT
REF
EXT
EXT
level gradually increases together with SS level. V
V
V
OUT
OUT
R2
R2
R1
R1
V
V
FB
FB
V
V
REF
REF
OUT
+
-
+
-
OP AMP
is rising up to input voltage level just after the power-on,
OP AMP
AMPOUT
AMPOUT
SS
SS
+
+
-
-
-
-
-
-
DTC
DTC
OUT
is also rising with balancing V
PWM Comparator
PWM Comparator
EXT
EXT
REF
level which
REF
and