Technical Note

8/18

BD9150MUV

www.rohm.com

2009.05 - Rev.A

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c

2009 ROHM Co., Ltd. All rights reserved.

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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.30 Soft start, Shutdown, UVLO timing chart

Hysteresis 100mV

Tss

Tss

Tss

Soft start

Standby mode

Operating mode

Standby

mode

Operating mode

Standby

mode

Operating mode

Standby mode

UVLO

EN

UVLO

UVLO

EN1,EN2