Product details


Number of series cells (Min) 3 Features Cell balancing, High-side driver, I2C support, Multi-cell support, Overcurrent in charging protection, Overcurrent in discharging protection, Separate MCU requirement, Short-current detection Vin (Max) (V) 34 Number of series cells (Max) 4 Operating temperature range (C) -25 to 85 Rating Catalog open-in-new Find other Battery monitors & balancers

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TSSOP (PW) 24 34 mm² 4.4 x 7.8 open-in-new Find other Battery monitors & balancers


  • 3- or 4-Cell Series Protection Control
  • Autonomous Overcurrent and Short Circuit Protection
  • Provides Individual Cell Voltages to Battery Management Host
  • Integrated Cell Balancing Control
  • I2C Compatible User Interface Allows Access to Battery Information
  • User Control to Initiate Protection
  • Integrated 3.3-V 25-mA LDO
  • Programmable Shutdown and Brownout Control
  • Provides Drive for Three External FETs
  • Low Supply Current of 140 µA Typical
  • Programmable Threshold and Delay for Short Circuit Current Protection
  • Provides Drive for Three External FETs
  • Can Directly Interface With bq2083/5 for Complete Battery Management Solution
    • Notebook computer battery packs
    • Test equipment

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The bq29311 is a three- or four-cell lithium-ion battery pack protection analog front end (AFE) IC that incorporates a 3.3-V 25-mA low-dropout regulator (LDO) and an I2C compatible interface to extract battery parameters such as cell voltages and control output status. Other parameters, such as overcurrent protection threshold and delay, can also be programmed into the bq29311 to increase the flexibility of the battery management system.

The bq29311 provides safety protection in overcurrent, short circuit, overvoltage, and undervoltage conditions via control from the battery management host. In overcurrent and short-circuit conditions the bq29311 can activate the FET drive as a secondary protection level. The communications interface allows the host to control and observe the current status of the protection, to set overcurrent levels for charge and discharge, to set the overcurrent blanking delay time, short-circuit threshold levels, and short-circuit blanking delay time, and to program for the VREG shutdown voltage and brownout-detection thresholds.

Each cell is balanced by a discharge path, which is enabled by the internal control registers accessible through the I2C compatible interface. The maximum current is set by an external series resistor with an absolute maximum value of 10 mA discharge current per cell.

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BQ76920 ACTIVE 3 to 5-Series Cell Li-Ion and Li-Phosphate Battery Monitor (bq76940 Family) This product is a 3-s - 5-s monitor with an integrated ADC.
BQ76925 ACTIVE Analog front end for 3 to 6 series lithium-ion cells This product is a 3-s - 5-s monitor with out an integrated ADC.

Technical documentation

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Type Title Date
* Datasheet bq29311 - Three- and 4-Cell Lithium-Ion or Lithium-Polymer Battery Protection IC datasheet (Rev. D) Sep. 19, 2002
Application notes Cell-Balancing in the bq208x Advanced Gas Gauge Solutions Mar. 17, 2004
Application notes bq2083 and bq2085 Board Offset Characterization and Compensation Jan. 30, 2004
Application notes Avoiding Clock Jitter with the bq2085 Advanced Gas Gauge Oct. 20, 2003

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