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Original question:

BQ76952: About the device parameter range on the typical circuit diagram of bq76952

BQ76952: DEFTOFF pin EOS damage,IiC can't use

Hui Cao22
Expert 1075 points
Part Number: BQ76952

Tool/software:

The BQ76952PFBR communicates with the main control unit through the IIC. After the BQ76952PFBR is powered on, the battery voltage data uploaded by the AFE is sometimes unavailable, and the main control unit reports a communication fault. Then we did the failure analysis, and it was found in the analysis report that PIN30-DEFTOFF suffered electrical damage. Is there any causal relationship between this and IIC's failure to communicate after a period of time? I didn't see any connection between the two from the DEFTOFF pin equivalence diagram.

This pin is suspended, how can we prevent EOS

  • 0
    TI__Genius 17835 points

    Hello Hui,

    Hui Cao22 said:
    After the BQ76952PFBR is powered on, the battery voltage data uploaded by the AFE is sometimes unavailable, and the main control unit reports a communication fault.

    Can you clarify more about this? Is the device NACKing or is the SCL line held low? Do you have any logic analyzer files of this? What was the voltage of REG18 and REG1?

    Hui Cao22 said:
    PIN30-DEFTOFF suffered electrical damage.

    If the IC was damaged, it can be difficult to determine its behavior. Do you mind sharing the circuitry around the DFETOFF pin?

    Depending on how it’s configured, the pin will have different recommended operating voltage ranges. This is shown below and can be found in Section 7.3 Recommended Operating Conditions of the datasheet.



    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Expert 1075 points

    1. For abnormal communication, please see the related description in another post: e2e.ti.com/.../bq76952-the-last-ack -frame-does-not-respond/5615167#5615167

    2. The PIN30 pin function is not in use. It is floating according to the recommended datasheet, and there is no circuit around it

  • 0 in reply to Hui Cao22
    TI__Genius 17835 points

    Hello Hui,

    Thank you for your patience. 

    Hui Cao22 said:
    For abnormal communication, please see the related description in another post: e2e.ti.com/.../bq76952-the-last-ack -frame-does-not-respond/5615167#5615167

    Are you in CRC mode at this point of time?

    Hui Cao22 said:
    2. The PIN30 pin function is not in use. It is floating according to the recommended datasheet, and there is no circuit around it

    Have you tried connecting DFETOFF to VSS as well to see if that has helped? 

    Best Regards,
    Alexis