R1211D002B RICOH [RICOH electronics devices division], R1211D002B Datasheet - Page 13

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

(Step3)
operation becomes normal mode.
<Latch Protection Operation>
maximum duty cycle, charge to an external capacitor, C2 of DELAY pin starts. And maximum duty cycle
continues and the voltage of DELAY pin reaches delay voltage detector threshold, V
and turns off the external power MOSFET.
terms of R1211x002B/D version. Otherwise, make supply voltage down to UVLO detector threshold or lower,
and make it rise up to the normal input voltage.
pin is fixed at GND level.
the next formula.
delay pin outputs "L".
When SS reaches 1V, soft-start operation finishes. V
The operation of Latch protection circuit is as follows: When AMPOUT becomes "H" and the IC detects
To release the latch protection operation, make the IC be standby mode with CE pin and make it active in
During the soft-start time, if the duty cycle may be the maximum, protection circuit does not work and DELAY
The delay time of latch protection can be calculated with C2, V
t=C2 × V
Once after the maximum duty is detected and released before delay time, charge to the capacitor is halt and
DLY
/I
DLY1
EXT
Normal
AMPOUT
SS,V
Step1
REF
Output Short
V
FB
AMPOUT
Maxduty Operation
DELAY
Step2
V
V
OUT
IN
REF
becomes constant voltage (=1V). Then the switching
DLY
, and Delay Pin Charge Current, I
Latched
Step3
V
DLY
DLY
SS
V
DTC
AMPOUT
AMPOUT
DTC
, outputs "L" to EXT pin
FB
,V
REF
DLY1
R1211x
, as in
13