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BQ76200: Power management forum

Sebastian de Leon
Prodigy 190 points
Part Number: BQ76200
Other Parts Discussed in Thread: TIDA-010030,

Hi,

I continue studying the high side fet circuits on the TIDA-010030.

I added to my readings the app note regarding output reverse voltage considerations for the BQ76200. My questions are now specifically regarding the implementation of the reverse voltage protection in the TIDA-010030.

1. Considering we have a TVS (D48) in parallel with the output, that will short circuit the output if any reverse voltage occurs in between PACK+/PACK- terminals, when will the reverse voltage protection (Q23) circuit act? (Why is it necessary having a TVS?)

2. I see R115, R113 and R109 were dimensioned as 0.1W resistors. If the reverse voltage is a voltage of more than 10V or so, these resistors will need to dissipate much more power than 0.1W. Why they were dimensioned in that way? I feel it has to do with the presence of the TVS but I'm not sure why.

Thanks very much!!!!

  • 0
    TI__Expert 3356 points

    Hi,

    1. you are right, the TVS will short PACK+ and PACK- when reverse voltage happens. The circuit will give another protection if the reverse power is large. 

    2. yes, long time, high reverse voltage will damage R109, R113, R115. In TIDA-010030, i assume that the reverse voltage will not last very long time. if you are considering long time reverse voltage, recommend to use larger power resisters. 

    Best Regards,

    Ryan