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BQ76952: Problems found in the 16s project.

Part Number: BQ76952
Other Parts Discussed in Thread: BQSTUDIO, BQ40Z50-R1

Hi TI Experts,

         I am using bq76952 to develop a 16 series battery project, but the following problems occurred, please help me.

        1. When the 10K NTC is attached, pull TS2 to GND, and the chip cannot wake up from shutdown. But after the 10K NTC is removed, it is OK. Is it possible to remove 10K NTC?

        2. Because my project needs MCU to control pre discharge MOS and main discharge MOS separately. But there seems to be no way to control it alone.

             Is there any other way to control pre discharge MOS and main discharge MOS separately?

 

        3. The internal temperature of the chip cannot be calibrated. Can the internal temperature of the next version be calibrated?

  

         4. 1A discharge can not be automatically recovered, which means that the load is discharged with 1A. After I let the discharge MOS disable, the discharged MOS can not be enabled again. Sending the command to enabled the MOS has no effect. It seems that the MOS is making a gap noise.

        

      

  • Hi,

    1. When the 10K NTC is attached, pull TS2 to GND, and the chip cannot wake up from shutdown. But after the 10K NTC is removed, it is OK. Is it possible to remove 10K NTC? If a thermistor is connected, it may prevent the part from fully entering Shutdown, so it is best not to use TS2 for a thermistor measurement if you plan to use TS2 to bring the device out of Shutdown. 

    2. Because my project needs MCU to control pre discharge MOS and main discharge MOS separately. But there seems to be no way to control it alone.

                 Is there any other way to control pre discharge MOS and main discharge MOS separately? There are commands to control these independently, but they are only available in FET Test Mode. The commands are PDSGTEST() and PCHGTEST(). To use these commands the FET_EN bit must be set to zero in the Manufacturing Status register.

     

            3. The internal temperature of the chip cannot be calibrated. Can the internal temperature of the next version be calibrated? You should be able to calibrate internal temperature. Did you try this using BQStudio?

      

             4. 1A discharge can not be automatically recovered, which means that the load is discharged with 1A. After I let the discharge MOS disable, the discharged MOS can not be enabled again. Sending the command to enabled the MOS has no effect. It seems that the MOS is making a gap noise. I am not sure what is causing this. How is the FET getting disabled? Is it through a protection triggering or is it getting disabled unexpectedly?

  • Hi Matt,

            3. The internal temperature of the chip cannot be calibrated. Can the internal temperature of the next version be calibrated? You should be able to calibrate internal temperature. Did you try this using BQStudio?

            Yes, The version of bqstudio is BatteryManagementStudio-1.3.101_Build1, the version of bq76952 FW is Monitor_7695_0_28-bq76952.bqz .

             The internal temperature of IC, I have tried several times, can not be calibrated.

             4. 1A discharge can not be automatically recovered, which means that the load is discharged with 1A. After I let the discharge MOS disable, the discharged MOS can not be enabled again. Sending the command to enabled the MOS has no effect. It seems that the MOS is making a gap noise. I am not sure what is causing this. How is the FET getting disabled? Is it through a protection triggering or is it getting disabled unexpectedly?

              I use bqstudio to send a command to turn off the discharge MOS, and then send a command to turn on the discharge MOS (the load remains on), but the discharge MOS cannot be turned on.

  • Hi Matt,

           The red part has been corrected,

            3. The internal temperature of the chip cannot be calibrated. Can the internal temperature of the next version be calibrated? You should be able to calibrate internal temperature. Did you try this using BQStudio?

            Yes, The version of bqstudio is BatteryManagementStudio-1.3.101_Build1, the version of bq76952 FW is Monitor_7695_0_24-bq76952.bqz .

             The internal temperature of IC, I have tried several times, can not be calibrated.

             4. 1A discharge can not be automatically recovered, which means that the load is discharged with 1A. After I let the discharge MOS disable, the discharged MOS can not be enabled again. Sending the command to enabled the MOS has no effect. It seems that the MOS is making a gap noise. I am not sure what is causing this. How is the FET getting disabled? Is it through a protection triggering or is it getting disabled unexpectedly?

              I use bqstudio to send a command to turn off the discharge MOS, and then send a command to turn on the discharge MOS (the load remains on), but the discharge MOS cannot be turned on.

  • 3. The internal temperature calibration should work for the version of the device you are using and you are using the latest BQStudio software. After you check the box next to the Internal sensor (in the Calibration Window) and click 'Calibrate Temperature', you should see a green checkbox showing that calibration is competed. If you look at the Data Memory screen, the Internal Temp Offset value should have changed to a new value (the default is 0.0). You can try to manually change this value and the Internal temperature reading should change.

    If you are using a newer version of the device, then the calibration register addresses have changed which may cause issues if you do not have an new .bqz file for the new version.

    4. Which commands are you using to enable and disable the DSG FET? Have you configured the FET Options register to enable Host FET commands?

    Best regards,

    Matt

  • Hi Matt,

      4. It's a hardware problem, not a software problem.

    If I use the All_FET_OFF command to turn off all the FET's first. Then set the load to 0.2A and keep it on, and then use the All_FET_ON command to turn on all the FET. This situation has no effect and the FET cannot be enabled.

    However, I put the load in the OFF state first, and then use the All_FET_ON command to turn on all the FETs. Then this situation is effective, and the FET can be turned on normally.

  • Can you check the device status registers to see if one of the protections is triggered and preventing the FET from turning on? You can check all of the SafetyAlert and SafetyStatus registers as well as the Battery Status, Alarm Status, and PF Status registers.

  • Hi Matt,

        No sign of protection occurred.

        Equivalent to discharge over-current protection, can not choose automatic recovery, can only choose to disconnect the load recovery.

         I tried, bq40z50-r1 doesn't have this problem.

        

  • Hi JM,

    I have not been able to reproduce this behavior on my board. I am able to use the ALL_FETS_ON and ALL_FETS_OFF commands while using a 1A discharge current. Can you send me your .gg file? 

    Thanks,

    Matt

  • Hi Matt,

         GG file has been uploaded, please check.

    The current sampling resistance is 1mR,

    Is your load always on? Is it like connecting a current absorbing resistor at the P + / P- terminal?

         4478.bq76952-16s-2020-9-19-1-alert.gg.csv

  • Hi Matt,

                I'm sorry, my fault. I've dealt with it. It's because of SCD.