SLUAAN9 February   2023 BQ769142 , BQ76942 , BQ76952 , BQ76972 , ISO1640 , LM5168

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Stacked AFE Communication
    1. 2.1 Data Communications
    2. 2.2 Control Signals
  5. 3High-Side N-Channel MOSFET
    1. 3.1 Discharge MOSFET Turn On and Off Processes
    2. 3.2 PACK Port High Voltage
    3. 3.3 Quickly Turning Off the Discharge MOSFET
  6. 4Current Consumption of Stacked Groups
  7. 5Summary
  8. 6References

5 Summary

The stacked BQ769x2 family monitor design is able to monitor 60 V and above Li-ion, LiFePO4 battery packs and achieve robust and fast high-side MOSFET drive to secure battery safety without external driver devices. This document analyzed some external discrete components in detail to describe how those parts benefit the data and commands communications between the host MCU and both the top and bottom BQ769x2. The high-side MOSFET drive architecture benefits system safety and communications but requires further design efforts to secure robust and safe MOSFET switching. The stacked architecture causes group imbalance because of current consumption gaps between the stacked groups, harming the total battery run time and lifetime. Several designs are introduced in this document to shrink the current gaps at different working conditions. The TIDA-010247 is a good reference of stacked BQ769x2 family monitor design, for 60 V and above battery packs designs.