HM5904 datasheet(10/15 Pages) HMSEMI

10 / 15 page

Function Description

For Battery Charging

Operation

The HM5904 is with a linear battery charger designed primarily for charging single cell lithium-ion

battery. The charger uses a constant-current/constant-voltage charging algorithm with programmable

current. Charging current can be programmed up to 1A by an external single resistor. The HM5904

includes an internal P-channel power MOSFET and thermal regulation circuitry. No blocking diode or

external sense resistor are required. Thus, the basic charger circuit requires only two external

components. Furthermore, The HM5904 is capable of operating from a USB power source.

Normal Charge Cycle

A charge cycle begins when the voltage at the VIN pin rises above the UVLO threshold. If the BAT

pin voltage is smaller than 2.8V, the charger enter trickle charge mode. In this mode, the HM5904

supplies approximately 1/10 the programmed charging current to bring the battery voltage up to a safe

level for full current charging. When the BAT pin voltage rises above 2.8V, the charger enters

constant-current mode, where the full programmed charge current is supplied to the battery. When the

BAT pin approaches the final float voltage (4.2V), the HM5904 enters the constant-voltage mode and

the charge current begins to decrease. When the charge current drops to 1/10 of the programmed

value, the charge cycle ended.

Programming Charge Current

The charge current is programmed by a single resistor connected from the PROG pin to ground.

The battery charging current is 1150 times the current flowing out of the PROG pin. The required

resistor value can be calculated from the charge current with following equation:

RPROG=

)

MAX

(

CHG

1150

The instantaneous charging current may differ from above equation in trickle or constant voltage

modes. The instantaneous charging current provided to the battery can be determined by monitoring

the PROG pin voltage at any time with the following equation:

ICHG=

1150

PROG

HM5904 Datenblatt(PDF) 10 Page - Shenzhen Huazhimei Semiconductor Co., Ltd