BD9111NV_09 Datasheet, PDF (7/14 Pages) Rohm – Output 2A or More High Efficiency Step-down Switching Regulator with Built-in Power MOSFET

BD9111NV
Technical Note
●Description of operations
・Soft-start function
EN terminal shifted to “High” activates a soft-starter to gradually establish the output voltage with the current limited during
startup, by which it is possible to prevent an overshoot of output voltage and an inrush current.
・Shutdown function
With EN terminal shifted to “Low”, the device turns to Standby Mode, and all the function blocks including reference
voltage circuit, internal oscillator and drivers are turned to OFF. Circuit current during standby is 0μF (Typ.).
・UVLO function
Detects whether the input voltage sufficient to secure the output voltage of this IC is supplied. And the hysteresis width of
100mV (Typ.) is provided to prevent output chattering.
Hysteresis 100mV
VCC
EN
VOUT
Standby mode
Tss
Soft start
Operating mode
Tss
Tss
Standby
mode
Operating mode
Standby
mode
Operating mode
Standby mode
UVLO
UVLO
EN
UVLO
Fig.24 Soft start, Shutdown, UVLO timing chart
・Short-current protection circuit with time delay function
Turns OFF the output to protect the IC from breakdown when the incorporated current limiter is activated continuously for
the fixed time(TLATCH) or more. The output thus held tuned OFF may be recovered by restarting EN or by re-unlocking
UVLO.
EN
Output Short circuit
Threshold Voltage
VOUT
IL Limit
IL
Output OFF
latch
Standby
mode
t1<TLATCH
Operating mode
t2=TLATCH
Standby
mode
Operating mode
EN
Timer latch
EN
Fig.25 Short-current protection circuit with time delay timing chart
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2009.05 - Rev.A