General Description

The MAX1781 smart battery-pack controller integrates

a user-programmable microcontroller core, a Coulombcounting fuel gauge, a multi-channel data-acquisition

unit, and an SMBus v1.1 compliant master/slave

SMBus interface. The 8-bit, RISC microcontroller core

has an integrated 12k bytes of user programmable

EEPROM, which provides battery-pack designers with

complete flexibility in developing fuel gauging and

control algorithms. The MAX1781 is equipped with

full ICE (in-circuit emulator) capability for efficient

firmware development and debugging.

The 16-bit data-acquisition unit measures individual

cell voltages, cell stack voltage, chip internal/external

temperature, and two general purpose analog inputs.

Individual cell voltage measurements with 0.5%

accuracy and over-current protection allow the

MAX1781 to eliminate a separate 1st level protection

IC. Adjustable over-current thresholds and delay

timers provide a flexible solution.

The integrating fuel gauge module provides a typical

input offset of less than 1uV, and gain accuracy of

better than 1% with no trimming required during pack

manufacture. The MAX1781 has a wide 4V to 28V

operating voltage range. The IC is available in a 7mm

x 7mm 48-TQFN package with a maximum thickness

of 0.8mm.

Features

¨ Accurate Fuel Gauge Uses V to F Method

· <1µV Input Offset Voltage

· <1% Gain Accuracy

· No Calibration Required

¨ 8-bit RISC Microcontroller Core

¨ 12k Bytes of Program/Data EEPROM

¨ 64 Bytes of Byte Writeable EEPROM

¨ 264 Bytes of RAM

¨ Watchdog Timer

¨ ICE for Firmware Debugging

¨ Integrated Development Environment (IDE)

· C Compiler

· Inline Assembler

¨ Eliminates Separate Primary-Protection IC

· Individual Cell Voltage Measurements with

0.5% accuracy

· Built-In Protection MOSFET Gate Drivers

· 8% Accurate Overcurrent Protection

· Programmable Over-Current Delay Timers

¨ SMBus v1.1-Compliant, with Master Capability

¨ Typical Operating Current <120µA

¨ Typical Shutdown Current <10nA

¨ Integrated 32kHz Oscillator: No Crystal

¨ Fully Integrated LDO (VIN = 4V to 28V)