R1224N122G RICOH [RICOH electronics devices division], R1224N122G Datasheet - Page 13

• Manufacturer Part Number: R1224N122G
• Description: PWM/VFM step-down DC/DC Converter
• Manufacturer: RICOH [RICOH electronics devices division]

TIMING CHART
operating with large current, stable operating, input voltage falling, input voltage recovering, and stable
operating.
pre-standby.
operation finishes, the operation becomes stable.
the delay time of protection circuit. (The current value depends on the circuit.)
soft-start operation starts. After the soft-start operation, EXT signal will be “L”, but if the large current is still
flowing, after the delay time of protection circuit passes, reset protection circuit will work again, the operation will
be continuously repeated unless the cause of large current flowing is not removed.
stable one.
one after the soft-start operation.
circuit may be ready to work, therefore, after the delay time of protection circuit, EXT will be “H”.
spre-standby.
finishes, the operation becomes stable.
The timing chart shown above describes the changing process of input voltage rising, stable operating,
First, until when the input voltage (V
Second, after V
If too large current flows through the circuit because of short or other reasons, EXT signal ignores that during
After the delay time passes, reset protection works, or EXT signal will be “H”, then output will turn off, then
Once the cause of the large current flowing is removed, within the delay time, the operation will be back to the
If the timing for release the large current is in the protection process, the operation will be back to the normal
If the V
Further, if the V
After that, if V
Then after V
IN
becomes lower than the set V
V
CE
EXT
V
IN
OUT
IN
becomes beyond the UVLO threshold, soft-start operation starts, when the soft-start operation
IN
IN
V
Voltage
V
Voltage
IN
rises, until when the V
OUT
OUT
is lower than UVLO voltage, the circuit inside will be stopped by UVLO function.
becomes beyond the UVLO threshold, soft-start operation starts, when the soft-start
Set Output
Set Output
Input Voltage
Rising Time
Soft Start
Operation
Stable
UVLO Voltage
IN
) reaches UVLO voltage, the circuit inside keeps the condition of
IN
OUT
V
V
reaches UVLO voltage, the circuit inside keeps the condition of
, that situation is same as large current condition, so protection
OUT
OUT
Protection Circuit Delay Time
Set Output Voltage
Set Output Voltage
Soft Start
Reset Protection
Soft Start
Operation
Stable
UVLO Reset
Soft Start
Operation
Stable
R1224N
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