UB280 datasheet(6/9 Pages) UTC

6 / 9 page

UB280

Preliminary

CMOS IC

UNISONIC TECHNOLOGIES CO., LTD

6 of 9

www.unisonic.com.tw

QW-R128-003.a

OPERAT I ON (Cont .)

3. Discharging overcurrent detector, Short detector

In the state of chargable and dischargabe, if the VM terminal voltage becomes higher than the discharging

overcurrent detection voltage (VDET3) by short of loads, etc., it will detect discharging overcurrent state. If the VM

terminal voltage becomes higher than short detection voltage, it will detect discharging overcurrent state, too. And

then the DO terminal outputs low level, so the external discharging control Nch MOSFET turns OFF, and it protects

from large current discharging.

The discharging overcurrent detection has delay time decided internally. When the VM terminal voltage becomes

higher than the discharging overcurrent detection voltage, it will not detect discharging overcurrent, if the VM terminal

voltage becomes lower than the discharging overcurrent detection voltage within the discharging overcurrent

detection delay time. More0ver, the discharging overcurrent release delay time exists, too.

The short detection delay time (Typ.500us) decided internally exists, too.

The discharging overcurrent release resistance is built into between VM terminal and VSS terminal. In the state of

discharging overcurrent or short, if the load is opened, VM terminal is pulled down to the VSS via the discharging

overcurrent release resistance. And when the VM terminal voltage becomes lower than the discharging overcurrent

detection voltage, it will automatically release discharging overcurrent or short state. The discharging overcurrent

release resistance turns ON, if discharging overcurrent or short is detected. On the normal state (chargable and

dischargable state), the discharging overcurrent release resistance is OFFed.

4. DS (Delay Shortening) function

The delay time of overcharge detection and overdischarge detection can be shortened by making the DS pin to

VDD level voltage. In the DS pin, the pull-down resistance of 15kohm is connected between VSS. Please open the DS

pin when using usually.

UB280 Datasheet(PDF) 6 Page - Unisonic Technologies