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BQ76952: Questions about the pre-loaded PDSG of bq76952

JH Zhang
Prodigy 210 points
Part Number: BQ76952

Hi TI experts，

       I have configured the bq76952 in semi-autonomous mode, that is, HOST_FET_EN=1. In this case, how can I send a command to turn on the PDSG first, and then send a command to turn on the discharge MOS. Now I can only turn on the DSG, but the PDSG cannot be turned on. Is there a corresponding description in the design document or TRM document?

  • 0
    TI__Expert 5645 points

    Hi JH, 

    In observance of the September 4 US Holiday, we will be out of office till September 5. 

    Regards, 

    Arelis G. Guerrero

  • 0
    TI__Mastermind 25605 points

    Hi JH,

    Please double check that Settings:FET:FET Options[PDSG_EN] = 1. That bit needs to be set to enable PDSG functionality. Section 5.2.3.2.2: PREDISCHARGE Mode of the TRM details the PDSG mode and the necessary settings to use it.

    See the image below, taken from Section 5.2.2: High-Side NFET Drivers of the TRM. This section details the commands the host can write while in partially autonomous mode to control the FETs, including the PDSG FET.

    Regards,

    Max Verboncoeur

  • 0 in reply to Max Verboncoeur
    Prodigy 210 points

    Hi Max,

    I have set Settings:FET:FET Options[PDSG_EN] = 1, HOST_FET_EN=1 and FET_EN=1, in this partial autonomous mode, I cannot issue a separate command to open the PDSG first, set the time and then send the command to open the DSG, it seems After I enable PDSG, it will be linked with DSG.
    In 5.2.3.2 of the TRM file, it is described that 0x001C PDSGTEST() works in FET test mode, while 0x0096 ALL_FETS_ON() turns on all FETs, and 0x0097 FET_CONTROL() cannot control the PDSG pin individually.
    That is to say, in partial autonomous mode, after configuring PDSG_EN and PREDISCHARGE, use the 0x0096 ALL_FETS_ON() command to turn on the PDSG first, delay ≤2550ms or voltage difference ≤2550mV and then turn on the DSG, PDSG cannot send commands and control alone, right?

  • +1 in reply to JH Zhang
    TI__Mastermind 25605 points

    Hi JH,

    Unfortunately, there is no way to enable just the PDSG FET outside of the test mode without starting the delay/voltage comparison to transition to the DSG FET.

    Regards,

    Max Verboncoeur