1 Features

• 4-, 5-, 6-, 7-, or 8-Series Cell Protection

• Individual Cell-Voltage Monitoring

• Low-Side NMOS FET Drive for Charge and

Discharge Control

• Compatible With 1-mΩ Current-Sense Resistor

• Supply-Voltage Range From 5.6 V to 40 V

• Integrated 3.3-V Micro-Power LDO Regulator

• Low Supply Current

– Normal Mode: 50 μA, Typical

– Shutdown Mode, LDO OFF: 5 μA, Typical

• 38-Pin TSSOP Package

• Internal 50-mA Automatic Cell Balancing

2 Applications

• Cordless Power Tools

• Cordless Lawn Equipment

• Electric Bikes

• UPS

• Light Electric Vehicles (LEV)

3 Description

The bq77908A is a battery protection and cell balancing device intended for Li-Ion and Li-Polymer battery packs.

The bq77908A monitors 4- to 8-series individual cell voltages and provides fast-acting outputs that may be used

to drive N-channel MOSFETs to interrupt the power path. Activation delays and recovery methods for safety

conditions are fully programmable in non-volatile memory.

Automatic cell balancing is provided using internal 50-mA cell circuits. A robust balancing algorithm ensures

optimum performance by maintaining all cell voltages in balance. Balancing may be configured to operate at all

times, only during charge, or can be disabled completely.