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New TI Gas Gauge, Protection Chipset Improves Battery Life and System Protection for Multi-Cell Battery Packs

Aug 13, 2003

DALLAS (Aug. 13, 2003) - Texas Instruments Incorporated (TI) (NYSE: TXN) today announced a new chipset featuring three advanced battery management integrated circuits (ICs) for two-, three- or four-series cell battery packs used in portable medical appliances, notebook computers, test and measurement and industrial equipment. TI´s new battery fuel gauge, protection analog front end (AFE) chip and secondary protection device provide portable designers with reduced quiescent current, increased efficiency and protection, while maintaining lower component count and cost. (See power.ti.com/sc03162.)

TI's highly efficient bq2084 Smart Battery Specification (SBS) version 1.1-compliant gas gauge maintains an accurate record of available charge in lithium-ion (Li-Ion) or lithium-polymer (Li-Poly) batteries and is a key piece of the battery management chipset. The device monitors capacity and other critical parameters of the battery pack, and reports the information to the system host controller over a system management bus (SMBus) interface. The host controller, such as a digital signal processor (DSP), manages remaining battery power to extend system run time.
The bq2084 provides light emitting diode (LED) display drivers and a push-button input to depict remaining battery capacity from full to empty in 20 percent, 25 percent or 33 percent increments with a three-, four- or five-segment display.

Additional Features of bq2084:

  • Integrated Time Base Removes Need for External Crystal 
  • Integrated FLASH Memory Eliminates Need for External Configuration with EEPROM 
  • Charge Flow Measurement Using a High Resolution 16-Bit Integrated, Self-Calibrating Converter with Better than 3-nVh Resolution and Offset Error Less than 1-uV 
  • 16-Bit Delta Sigma Converter for Accurate Voltage and Temperature Measurements 
  • Programmable Cell Modeling for Maximum Battery Fuel Gauge Accuracy

TI offers the gas gauge with the new


AFE protection circuit. The device provides safety protection for overcharge, overload, short-circuit, overvoltage and undervoltage conditions with the battery management host processor. In overload and short-circuit conditions, the


turns the FET drive off autonomously and dependant of the internal configuration setting.

In addition to incorporating a 3.3-V, 25-mA low dropout regulator (LDO), the


integrates an I2C compatible interface to enable measurement of battery parameters such as cell voltages and pack temperature. Current protection thresholds and delays, cell balancing drive, power modes and feature configurations can be programmed into the


to increase the flexibility of the battery management system.

Additional Features of bq29312:

  • 2-, 3- or 4-Cell Series Protection Control 
  • Individual Cell Voltages and Battery Voltage Provided to Battery Management Host 
  • Integrated Cell Balancing Drive 
  • Programmable Threshold and Delay for Over Load and Short Circuit During Charge and Discharge 
  • System Alert Interrupt Output 
  • Host Control Can Initiate Sleep Power Mode and Ship Mode 
  • Low Supply Current of 60-uA Typical

TI also offers the new


secondary protection IC, which incorporates a highly accurate independent precision overvoltage detection circuit. With the secondary voltage protector, each battery cell in a multi-cell battery pack is compared to an internal reference voltage. If one cell gets into an overvoltage condition, the


will wait over a programmed period of time and set an output to drive an external FET, which can be used to burn a chemical fuse to further protect the system.

Additional Features of bq29400:

  • 2-, 3- or 4-Cell Series Secondary Protection Control 
  • Low Power Consumption ICC less than 2uA
  • High Accuracy Over Sense Voltage: 4.35 V 25 mV 
  • Prefixed Protection Threshold Voltage 
  • Programmable Delay Time 
  • High Power Supply Ripple Rejection 
  • Stable During Pulse Charge Operation

Pricing and Availability

All three components of the chipset are available now from TI and its authorized distributors. The bq2084 comes in a 38-pin TSSOP package, the bq29312 in a 24-pin TSSOP and the bq29400 comes in an 8-pin TSSOP package. Suggested resale pricing in 1,000 piece quantities include $4.35 each for the bq2084, $1.20 each for bq29312 and $0.45 for the bq29400. A combined evaluation module is available for all three devices at power.ti.com.