1 Features

1• SMBus Host-controlled NMOS-NMOS

synchronous buck converter with programmable

615kHz, 750kHz, and 885kHz switching

frequencies

• Automatic N-channel MOSFET selection of

system power source from adapter or battery

driven by internal charge pumps

• Enhanced safety features for over voltage

protection, over current protection, battery,

inductor and MOSFET short circuit protection

• Programmable input current, charge voltage,

charge current limits

– ±0.5% Charge voltage accuracy up to 19.2V

– ±3% Charge current accuracy up to 8.128A

– ±3% Input current accuracy up to 8.064A

– ±2% 20x Adapter current or charge current

amplifier output accuracy

• Programmable battery depletion threshold, and

battery LEARN function

• Programmable adapter detection and indicator

• Integrated soft start

• Integrated loop compensation

• Real time system control on ILIM pin to limit

charge current

• AC Adapter operating range 4.5V-24V

• 5μA Off-state battery discharge current

• 0.65mA (0.8mA max) Adapter standby quiescent

current

• 20-pin 3.5 x 3.5 mm2 VQFN Package

2 Applications

• Portable notebook computers, UMPC, Ultra-thin

notebook, and Netbook

• Handheld terminal

• Industrial and medical equipment

• Portable equipment

3 Description

The BQ24725A is a high-efficiency, synchronous

battery charger, offering low component count for

space-constraint, multi-chemistry battery charging

applications.

The BQ24725A utilizes two charge pumps to

separately drive n-channel MOSFETs (ACFET,

RBFET and BATFET) for automatic system power

source selection.

SMBus controlled input current, charge current, and

charge voltage DACs allow for very high regulation

accuracies that can be easily programmed by the

system power management micro-controller.

The BQ24725A uses internal input current register or

external ILIM pin to throttle down PWM modulation to

reduce the charge current.

The BQ24725A charges one, two, three or four series

Li+ cells.