HM5459 datasheet(4/6 Pages) HMSEMI

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Shenzhen H&M Semiconductor Co.Ltd

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HM5459

FUNCTIONAL DESCRIPTION

The HM5459 monitors the voltage and current of a battery and protects it from being

damaged due to overcharge voltage, over-discharge voltage, over-discharge current, and short

circuit conditions by disconnecting the battery from the load or charger. These functions are

required in order to operate the battery cell within specified limits.

The device requires only one external capacitor. The MOSFET is integrated and its RDS(ON) is

as low as 53mΩ typical.

Overcharge Condition

When the battery voltage becomes higher than the overcharge detection voltage (VDET1)

during charging under normal condition and the state continues for the overcharge detection delay

time (VDET1) or longer, the HM5459 turns the charging control FET off to stop charging. This

condition is called the overcharge condition. The overcharge condition is released in the following

two cases:

1: When the battery voltage drops below the overcharge release voltage (VRET1), the HM5459

turns the charging control FET on and returns to the normal condition.

2: When load is connected and discharging starts, the HM5459 turns the charging control FET

on and returns to the normal condition. The release mechanism is as follows: the discharging

current flows through an internal parasitic diode of the charging FET immediately after load is

connected and discharging starts, and the batt- pin voltage increases about 0.7 V (forward voltage

of the diode) from the GND pin voltage momentarily. The HM5459 detects this voltage and

releases the overcharge condition. Consequently, in the case that the battery voltage is equal to or

lower than the overcharge detection voltage (VDET1), the HM5459 returns to the normal condition

immediately, but in the case the battery voltage is higher than the overcharge detection voltage

(VDET1), the chip does not return to the normal condition until the battery voltage drops below the

overcharge detection voltage (VDET1) even if the load is connected. In addition, if the batt- pin

voltage is equal to or lower than the over current 1 detection voltage when load is connected and

discharging starts, the chip does not return to the normal condition.

Over-discharge Condition

When the battery voltage drops below the over-discharge detection voltage ( VDET2) during

discharging under normal condition and it continues for the over-discharge detection delay time

(TVDET2) or longer, the HM5459 turns the discharging control FET off and stops discharging. This

condition is called over-discharge condition. After the discharging control FET is turned off, the

batt- pin is pulled up by the resistor between batt- and VDD in HM5459.

Meanwhile when batt- is bigger than 1.5V (typ.) (the load short-circuiting detection voltage),

the current of the chip is reduced to the power-down current (IPDN). This condition is called

power-down condition. The batt- and VDD pins are shorted by the resistor in the IC under the

over-discharge and power-down conditions. The power-down condition is released , when charger

is connected and the potential difference between batt- and VDD becomes 1.3 V (typ.) or higher

(load short-circuiting detection voltage). At this time, the FET is still off. When the battery voltage

becomes the over-discharge detection voltage (VDET2) or higher (see note), the HM5459 turns the

FET on and changes to the normal condition from the over- discharge condition.

HM5459 Datasheet(PDF) 4 Page - Shenzhen Huazhimei Semiconductor Co., Ltd

HM5459 Datasheet(HTML) 4 Page - Shenzhen Huazhimei Semiconductor Co., Ltd

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