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BQ76952: How to set the DSG FET driver remain off by default after configuration, and only turn on the DSG FET until the MCU sends a command?

Weiping Guo
Prodigy 20 points
Part Number: BQ76952

Tool/software:

We want the DSG FET to remain off by default after configuration, and not allow the DSG FET to be turned on until the MCU sends a command. However, the reality is that even if we set FET Options[FET_INIT_OFF] to 1, the DSG FET will still turn on, which is not the expected result.

Here are the register configuration:

Mfg Status Init --- 0x0010
FET Options -- 0x3C
Chg Pump Control -- 0x01
DSG FET Protections A / B / C --- 0x00
Enabled Protections A / B / C --- 0x00

  • 0
    TI__Expert 4320 points

    Hi,

    When the device is powered on the FETs are not on unless the FET_ENABLE command is sent. 

    If you want to control turning the FET off you could use the DFETOFF pin. You can refer to 12.7 CFETOFF, DFETOFF, and BOTHOFF Pin Functionality of the data sheet for more information.

    Best regards,

    Thomas Rainey

  • 0 in reply to Thomas Rainey
    Prodigy 20 points

    Hi,

    The phenomenon I can observe now is that after resetting BQ76952, setting Mfg Status Init [FET_EN] to 0, the DSG FET can be observed to be turned off. Then, sending the 0x0022 FET_ENABLE() command, it is found that the DSG FET is turned on.

    So, is it possible to keep the DSG FET turned off even after sending the 0x0022 FET-ENABLE() command, and only allow it to be turned on after I send the 0x0096 ALL-FETS-ON() command?

  • 0 in reply to Weiping Guo
    TI__Expert 4320 points

    Hello,

    The best way I can think of would be to use the DFETOFF pin. If this pin is asserted the DSG FET will not have the ability to be enabled. You can control this pin with an MCU. If you assert the pin the FET_ENABLE() command should not turn on the FET.

    Best regards,

    Thomas Rainey