Datasheet

Technical Note
BD9111NV
7/13
www.rohm.com
2010.04 - Rev.B
© 2010 ROHM Co., Ltd. All rights reserved.
●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.
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(T
LATCH) or more. The output thus held tuned OFF may be recovered by restarting EN or by re-unlocking
UVLO.
Fig.25 Short-current protection circuit with time delay timing chart
t2=TLATCH
Output OFF
latch
EN
V
OUT
Output Short circuit
Threshold Voltage
I
L
Standby
mode
Operating mode Operating mode
EN
Timer latch
EN
Standby
mode
IL Limi
t
t1<TLATCH
Hysteresis 100mV
Ts s Ts s Ts s
Soft start
Standby mode Operating mode
Standby
mode
Operating mode
Standby
mode
Operating mode
Standby mode
UVLO
EN UVLO
UVLO
VCC
EN
V
OU
T