BM2P034 datasheet(8/19 Pages) ROHM

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Datasheet

BM2PXX4 Series

TSZ02201-0F2F0A200070-1-2

28.NOV.2012.Rev.003

www.rohm.com

TSZ22111・15・001

(3) VCC pin protection function

BM2PXX4 built in VCC low voltage protection function of VCCUVLO (Under Voltage Lock Out), over voltage protection

function of VCC OVP (Over Voltage Protection) and VCC charge function that operates in case of dropping the VCC

voltage.

This function monitors VCC pin and prevent VCC pin from destroying switching MOSFET at abnormal voltage.

VCC charge function stabilizes the secondary output voltage to be charged from the high voltage line by start circuit at

dropping the VCC voltage.

(3-1) VCC UVLO ／ VCC OVP function

VCCUVLO is auto recovery comparator. VCCOVP is auto recovery comparator that has voltage hysteresis.

Refer to the operation figure-8.

VCCOVP operates detection in case of continuing VCC pin voltage > VOVP （typ=27.5V）.

This function built in mask time TLATCH（typ=100us）.By this function, this IC masks pin generated surge etc.

VCCuvlo1=13.5Vtyp

OFF

Vovp1=27.5Vtyp

Vchg2= 8.7Vtyp

OFF

VCCuvlo2 8.2Vtyp

Vovp1=23.5Vtyp

OFF

Vchg1=13.0Vtyp

Figure 8. VCC UVLO / OVP Timing Chart

A:DRAIN voltage input, VCC pin voltage starts rising.

B:VCC>Vuvlo1, DC/DC operation starts

C:VCC< VCHG1, VCC charge function operates and the VCC voltage is rise.

D:VCC > VCHG2, VCC charge function is stopped.

E:VCC > VOVP1 continues TLATCH(typ =100us), switching is stopped by the VCCOVP function.

F:VCC < VOVP2 , DC/DC operation restarts

G:VH is OPEN.VCC Voltage is fall.

H:Same as C.

I:Same as D.

J: VCC<Vuvlo2, DC/DC operation stops

BM2P034 Datasheet(PDF) 8 Page - Rohm