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BQ30Z554-R1: The action of shuntdown mode

chentsu chung
Mastermind 6180 points
Part Number: BQ30Z554-R1

Hi,

 

Customer now is testing battery and wants BQ30Z554 to enter shutdown mode, but sometimes the 3V3 still exist but DSG FET has already off, and the temp. of mosfet that connected to FUSE pin rise very high. Using tool to check the status of BQ30Z554, found that the flag of PTC fo PF, here are the questions:

 

1. what is the connection between PTC and FUSE, is PTC affect FUSE or FUSE affect PTC?

2. Is it possible that shutdown mode make this happen?

 

the mosefet in schematic below:


 

Thank you.

  • 0 in reply to chentsu chung
    TI__Intellectual 1365 points

    Hi Chentsu,

    I don't know your connection between FUSE and PTC but they should be separated. PTC should be connected to the Gnd. I believe R22 is connected to Gnd but please, find the reference circuit in Datasheet.  If PTC pin is high, it will trigger permanent failure and cause DSG/CHG FETs are off and Fuse pin goes high.

    It looks customer used 10kohm resistor instead of PTC. So, I suspect external noise triggers PTC failure.

    Shutdown mode can't cause this happen but PTC is monitored in shutdown mode as well as normal mode.