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.