SBAA885 October   2026 BQ76907-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Passive Balancing Mechanism of BQ76907
    1. 2.1 Balancing Current Path
    2. 2.2 Balancing Current
    3. 2.3 Balancing Time Estimation
  6. 3Particularity of Supercapacitor Systems
    1. 3.1 ESR and Voltage Recovery Effect
    2. 3.2 Impact on Balancing Strategy
  7. 4Balancing Scheme Design
  8. 5Reference Algorithm Implementation and Example
    1. 5.1 Algorithm Flow and Pseudocode
    2. 5.2 Design Example
  9. 6Conclusion
  10. 7References

Abstract

This document was translated from a simplified Chinese source. (ZHCAG91)

BQ76907-Q1 is a 2S–7S low-power battery monitoring and protection device, and supercapacitors have been listed as one of the supported objects in the datasheet. The device supports passive balancing initiated and controlled by the host, which can be implemented using integrated bypass paths or external balancing FETs. For systems requiring higher balancing currents, it is explicitly recommended to use external FET balancing circuits.

This paper targets a 5-series supercapacitor backup power system: the system provides a stable 12V charging power supply from vehicle 12V via Buck-Boost, and adopts a passive balancing scheme of external resistors plus MOSFETs. This paper focuses on how to better achieve the optimal scheme for all channels under the passive balancing architecture.