General Description

The MAX8731A is an SMBus™ programmable multichemistry battery charger. The MAX8731A uses a minimal command set to easily program the charge voltage, charge current, and adapter current limit.

The MAX8731A charges one to four Li+ series cells and delivers up to 8A charge current. The MAX8731A drives n-channel MOSFETs for improved efficiency and reduced cost. Low-offset current-sense amplifiers provide high accuracy with 10mΩ sense resistors.

The MAX8731A current-sense amplifiers provide high accuracy (3 at 3.5A) and also provide fast cycle-by cycle current-mode control to protect against battery short circuit and system load transients.

The charger employs dual remote sense, which reduces charge time by measuring the feedback voltage directly at the battery, improving accuracy of initial transition into constant-voltage mode. The MAX8731A provides 0.5 battery voltage accuracy directly at the battery terminal.

The MAX8731A provides a digital output that indicates the presence of the AC adapter, as well as an analog output that indicates the adapter current within 4 accuracy.

The MAX8731A is available in a small 5mm x 5mm, 28-pin, thin (0.8mm) QFN package. An evaluation kit is available to reduce design time. The MAX8731A is available in a lead-free package.

Features

♦ 0.5 Battery Voltage Accuracy

♦ 3 Input Current-Limit Accuracy

♦ 3 Charge-Current Accuracy

♦ SMBus 2-Wire Serial Interface

♦ Cycle-by-Cycle Current Limit

   Battery Short-Circuit Protection

   Fast Response for Pulse Charging

   Fast System-Load-Transient Response

♦ Dual-Remote-Sense Inputs

♦ Monitor Outputs for

   Adapter Current (4 Accuracy)

   AC Adapter Detection

♦ 11-Bit Battery Voltage Setting

♦ 6-Bit Charge-Current/Input-Current Setting

♦ 8A (max) Battery Charger Current

♦ 11A (max) Input Current

♦ +8V to +26V Input Voltage Range

♦ Charges Li+, NiMH, and NiCd Battery Chemistries

Applications

   Notebook Computers

   Tablet PCs

   Medical Devices

   Portable Equipment with Rechargeable Batteries