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

3 High-Side N-Channel MOSFET

The TIDA-010247 supports a high-side N-channel MOSFET architecture and uses the top BQ769x2 charge pump to drive the MOSFET on and off. The high-side MOSFET architecture always secures the ground connection, being good for communications between pack and outside but have new design challenges. Since the top BQ769x2 references the bottom stack voltage, when the top BQ769x2 tries to turn the DSG MOSFET off, the DSG pin voltage drops towards the LD pin voltage and finally to the bottom stack voltage (top BQ769x2 ground), the bottom stack voltage is too high to completely turn the DSG MOSFET off. The TIDA-010247 uses a discrete circuit (shown in #FIG_TG5_XXH_VVB) to make sure the DSG MOSFET turns off completely and quickly.


GUID-20221213-SS0I-6P8M-XFFJ-FZCTR7NFLCPF-low.gif

Figure 3-1 High-Side MOSFET Drive Circuit in TIDA-010247