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Datasheet

Datasheet

BM2PXX1F

TSZ02201-0F2F0A200020-1-2

24.Sep.2015.Rev.006

© 2012 ROHM Co., Ltd. All rights reserved.

www.rohm.com

TSZ22111・15・001

(3-2) VCC Charge function

After VCC charge function operates once the VCC pin >VUVLO1 and the DC/DC operation starts then the VCC pin

voltage drops to <VCHG1. At that time the VCC pin is charged from DRAIN pin through start circuit.

By this operation, BM2PXX1F doesn’t occur to start failure.

When VCC pin voltage rises to VCC >VCHG2, charge is stopped. The operations are shown in figure 9.

VCC

Switching

VH charge

charge

charge

OUTPUT

voltage

charge charge

AB C D E

F G H

VH

Figure 9. Charge operation VCC pin charge operation

A: DRAIN pin voltage rises, charge starts to VCC pin by the VCC charge function.

B: VCC > V

C: When DC/DC operation starts, the VCC voltage drops.

D: VCC < V

CHG1

E: VCC > V

CHG2

F: VCC < V

G: VCC > V

CHG1

H: After start of output voltage finished, VCC is charged by the auxiliary winding VCC pin stabilizes.