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)