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

1 Introduction

Because of the weight limit and longer endurance needs, the battery cell chemistry of the e-motorcycle, light electric vehicles, and garden tool battery packs is shifting from Lead-acid to Li-ion, Li-polymer, or Li-ion phosphate (LiFePO4) types and the pack voltage is shifting from 36 V or 48 V to 60 V or 72 V, or even higher. For 60 V and higher battery packs, two stacked BQ769x2 family monitors are required.

One critical requirement of a battery pack is how to attain safe use during the entire battery pack lifetime. The stacked BQ769x2 family monitor architecture spawns some challenges of how to monitor the information of all battery cells and detect unsafe working conditions, and how to control the on and off switches to protect the battery pack away from dangerous use-cases. TI released the TIDA-010247 reference design where a stacked BQ769x2 family monitors a battery-pack design with high-side N-MOSFET control. #FIG_TG5_XXH_VVB shows the TIDA-010247 block diagram. This document identifies the common design challenges in stacked BQ769x2 family monitor architecture and explains how to address the challenges.



Figure 1-1 TIDA-010247 Block Diagram