HM9902A datasheet(7/11 Pages) HMSEMI

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HM9902A

to overdischarge current, the HM9902A

stop discharging by overdischarge current

detection. In this case the recovery of battery

voltage is so slow that if battery voltage

after overdischarge voltage detection delay

time is still lower than overdischarge

detection voltage, the HM9902A shifts to

power-down.

is fixed to VDD potential. When the voltage

between the gate and the source of the

charging control FET becomes equal to or

higher than the turn-on voltage by the

charger voltage, the charging control FET

is turned on to start charging. At this time,

the discharging control FET is off and the

charging current flows through the internal

parasitic diode in the discharging control

FET. If the battery voltage becomes equal

to or higher than the overdischarge release

voltage (VDU), the normal condition returns.

Note

(1)

Some battery providers do not recommend

charging of completely discharged batteries. Please

refer to battery providers before the selection of 0 V

battery charging function.

(2)

The 0V battery charging function has higher

priority than the abnormal charge current detection

function. Consequently, a product with the 0 V

battery charging function charges a battery and

abnormal charge current cannot be detected during

the battery voltage is low (at most 1.8 V or lower).

(3)

When a battery is connected to the IC for the

first time, the IC may not enter the normal condition

in which discharging is possible. In this case, set

the VM pin voltage equal to the GND voltage (short

the VM and GND pins or connect a charger) to

enter the normal condition.

Figure 4. Overcurrent delay time

0V Battery Charging Function

(1) (2) (3)

This function enables the charging of a

connected battery whose voltage is 0 V by

self-discharge. When a charger having 0 V

battery start charging charger voltage

(V0CHA) or higher is connected between B+

and B- pins, the charging control FET gate

- 7 -

Shenzhen H&M Semiconductor Co.Ltd

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