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(the discharging control FET is turned on) as usual,

provided that the battery voltage reaches the

Overcurrent Condition

When the discharging current becomes

equal to or higher than a specified value

(the VM pin voltage is equal to or higher

than the overcurrent detection voltage)

during discharging under normal condition

and the state continues for the overcurrent

detection delay time or longer, the

HM9901 turns off the discharging control

FET to stop discharging. This condition is

called overcurrent condition. (The

overcurrent

includes overcurrent, or load short-

circuiting.)

The VM and GND pins are shorted

overcurrent condition. When a load is

connected, the VM pin voltage equals the

VDD voltage due to the load.

The overcurrent condition returns to the

normal condition when the load is released

and the impedance between the B+ and B-

pins becomes higher than the automatic

recoverable impedance. When the load is

removed, the VM pin goes back to the

GND potential since the VM pin is shorted

Detecting that the VM pin potential is lower

than the overcurrent detection voltage

condition.

Abnormal Charge Current Detection

If the VM pin voltage drops below the

charging under the normal condition and it

continues for the overcharge detection

turns the charging control FET off and

stops charging. This action is called

abnormal charge current detection.

Abnormal charge current detection works

when the discharging control FET is on

and the VM pin voltage drops below the

abnormal charge current flows into a

battery in the overdischarge condition, the

HM9901 consequently turns the

charging

control FET off and stops charging after

the battery voltage becomes the

overdischarge detection voltage and the

elapses.

Abnormal charge current detection is

released when the voltage difference

between VM pin and GND pin becomes

lower than the charger detection voltage

0 V battery charging function has higher

priority than the abnormal charge current

detection function, abnormal charge

current may not be detected by the product

with the 0 V battery charging function while

the battery voltage is low.

Load Short-circuiting condition

If voltage of VM pin is equal or below

the HM9901 will stop discharging and

battery is disconnected from load. The

maximum delay time to switch current off is

of VM pin is higher than short protection

disconnecting the load.

Delay Circuits

The detection delay time for overdischarge

current 2 and load short-circuiting starts

when overdischarge current 1 is detected.

As soon as overdischarge current 2 or load

short-circuiting is detected over detection

delay time for overdischarge current 2 or

load short- circuiting, the HM9901 stops

discharging. When battery voltage falls

below overdischarge detection voltage due

HM9901