bq2040

The bq2040 Gas Gauge IC With SMBus Interface is intended for battery-pack or in-system installation to maintain an accurate record of available battery charge. The bq2040 directly supports capacity monitoring for NiCd, NiMH, and Li-Ionbatterychemistries.


The bq2040 uses the System Management Bus v1.0 (SMBus) protocol and supports the Smart Battery Data (SBData) commands. The bq2040 also supports the SBData charge control functions. Battery state-of-charge, remaining capacity, remaining time, and chemistry are available over the serial link. Battery-charge state can be directly indicated using a four-segment LED display to graphically depict battery full-to-emptyin25%increments.


The bq2040 estimates battery selfdischarge based on an internal timer and temperature sensor and user-programmable rate information stored in external EEPROM.The bq2040 also automatically recalibrates or "learns" battery capacity in the full course of a discharge cyclefromfulltoempty.


The bq2040 may operate directly from three nickel chemistry cells. With the REF output and an external transistor, a simple, inexpensive regulator can be built to provide V_CC for other battery cell configurations.


An external EEPROM is used to program initial values into the bq2040 and is necessary for proper operation.