Multi-cell battery monitors scan 12 to 48-V industrial Li-ion batteries

May 26, 2014 // By Graham Prophet
Scalable monitors with built-in protection simplify design of 3- to 15-cell batteries used in power tools and e-bikes

Texas Instruments has introduced scalable, multi-cell battery monitors that improve battery pack safety and reduce design time of 12-V to 48-V lithium-ion and lithium-iron phosphate batteries used in e-bikes, power tools and energy storage systems. The new bq76920, bq76930 and bq76940 circuits protect and control 3- to 15-cell batteries when charging or operating in harsh environment conditions.

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

Designers can start their battery designs with three new reference boards;

18-V Battery Monitoring ( bq76920EVM) supports 3- to 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.

36-V Battery Monitoring ( bq76930EVM) supports 6- to 10-series cell batteries, and includes the bq76930, a battery management controller for monitoring and protection, an interface adapter and evaluation software.

48-V Battery Monitoring ( bq76940EVM) supports 9- to 15-cell batteries, and includes the bq76940, a battery management controller for complete monitoring and protection, an interface adapter and evaluation software.

Features include;

  1. Complete battery measurement: Accurately measures cell voltages, temperature and pack current to determine remaining battery capacity and battery state-of-health.
  2. Built-in hardware protection: Cell balancing, integrated analogue-to-digital converters and built-in hardware protection provide the highest degree of battery safety.
  3. Feature integration: Reduces board space as much 30%, and minimises bill of materials.
  4. Fast development time: Unified digital interface across all three devices – from 18 V to 48 V or higher – and saves significant time, effort and cost.

The bq76920 comes in a 20-pin, 4.4 by 6.5 mm