Monitors significantly improve battery pack safety

28th May 2014

Nat Bowers

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Datasheet

Efficiently protecting and controlling 3-15 cell batteries when charging or operating in harsh environment conditions, Texas Instruments has introduced the bq76920, bq76930 and bq76940 circuits. TI claims that these are the first scalable, multi-cell battery monitors that significantly improve battery pack safety and reduce design time of 12-48V lithium-ion and lithium-iron phosphate batteries used in e-bikes, power tools and energy storage systems.

The advanced monitors incorporate cell-balancing drivers, regulated output supplies and other unique features to reduce external component count and provide heightened protection against overvoltage, undervoltage and overcurrent conditions. Simplifying battery design and optimising board space, the bq76920 supports 3-5 series cells or typical 18V packs; the bq76930 manages up to 10 series cells or 36V packs; and bq76940 monitors up to 15 cells or typical 48V batteries.

The devices accurately measure cell voltages, temperature and pack current to determine remaining battery capacity and battery state-of-health. Cell balancing, integrated ADCs and built-in hardware protection provide the highest degree of battery safety. This integration Reduces board space as much 30%, and minimises bill of materials costs. A unified digital interface across all three devices and saves significant time, effort and cost.

Designers can jump-start their battery designs with three reference boards:

The bq76920EVM 18V Battery Monitoring EVM supports 3-5 series cell packs, and includes the bq76920, a battery management controller for complete monitoring and protection, an interface adapter and software to evaluate register control and configuration.
The bq76930EVM 36V Battery Monitoring EVM supports 6-10 series cell batteries, and includes the bq76930, a battery management controller for monitoring and protection, an interface adapter and evaluation software.
The bq76940EVM 48V Battery Monitoring EVM supports 9-15 cells, and includes the bq76940, a battery management controller for complete monitoring and protection, an interface adapter and evaluation software.

The bq76920, bq76930 and bq76940 multi-cell battery monitors are available in volume production now. The bq76920 comes in a 20-pin, 4.4x6.5mm TSSOP package with a suggested resale price of $1.50 (USD) each in 1,000 unit quantities; the bq76930 comes in a 30-pin, 4.4x7.8mm TSSOP package with a suggested resale price of $2.75 (USD) each in 1,000 unit quantities; and the bq76940 comes in a 44-pin, 4.4x11.3mm TSSOP package with a suggested resale price of $3.95 (USD) each in 1,000 unit quantities.