Product details


Cell chemistry Lead Acid, Li-Ion/Li-Polymer, NiCd, NiMH Number of series cells 2-4 Cells Communication interface SMBus Battery capacity (Min) (mAh) 800 Battery capacity (Max) (mAh) 10000 Implementation Pack External capacity indication LED Operating temperature range (C) 0 to 70 open-in-new Find other Battery fuel gauges

Package | Pins | Size

SOIC (D) 16 59 mm² 9.9 x 6 open-in-new Find other Battery fuel gauges


  • Provides accurate measurement of available charge in NiCd, NiMH, and Li-Ion batteries
  • Supports SBS v1.0 data set and two-wire interface
  • Monitors charge FET in Li-Ion pack protection circuit
  • Designed for battery pack integration
    - Low operating current
    - Complete circuit can fit on less than 3/4 square inch of PCB space
  • Supports SBS charge control commands for NiCd, NiMH, and Li-Ion
  • Drives a four-segment LED display for remaining capacity indication
  • 16-pin narrow SOIC
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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-Ion battery chemistries.

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-empty in 25% increments.

The bq2040 estimates battery self-discharge based on an internal timer and temperature sensor and user-programmable rate information stored in external EEPROM. The bq2040 also automatically recalibrates or \x93learns\x94 battery capacity in the full course of a discharge cycle from full to empty.

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 VCC for other battery cell configurations.

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

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BQ2060A ACTIVE Multi-chemistry SBS 1.1 compliant gas gauge with 5 LED drivers, Additional battery mgmt control This product is more accurate, SBS 1.1 Compliant, has faster communication capability and has a maintained design environment.

Technical documentation

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Type Title Date
* Datasheet Gas Gauge IC With SMBus Interface datasheet Sep. 05, 1999
Application notes Wide-Vin Battery-Charger Using SMBus MSP430 MCUs and bq Fuel Gauges (Rev. B) Jul. 12, 2019
User guides EV2200 PC Interface Board for Gas Gauge and Battery Monitor Evaluation (Rev. A) Jan. 04, 2006
Application notes bq2040-D111 to bq2040-C408 Change List Oct. 20, 2003
User guides bq2040 EVM Apr. 10, 2000
User guides bq2040 SBS v1.0 Gas Gauge Demonstration Module Apr. 10, 2000
User guides EV2200-40 Evaluation System User Guide (Rev. A) Mar. 13, 2000
User guides EV2200 PC Interface Board for Gas Gauge Evaluation Sep. 05, 1999
User guides EV2200-40 Evaluation System User Guide Sep. 05, 1999
Application notes U-513 Using the bq2040, Smart Battery System Gas Gauge IC Sep. 05, 1999

Design & development

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Software development

SLUC013.ZIP (2529 KB)

CAD/CAE symbols

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SOIC (D) 16 View options

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