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Original question:

BQ40Z80: ASCD test and DSG MOS burn

BQ40Z80: ASCD spec

Lin daphne
Prodigy 50 points
Part Number: BQ40Z80

Hello there,
I wonder if I use short circuit current around 400A/1ms, will this affect how IC works or cause other problems?
Also, I have another question. I know that the datasheet says to use 1~3mΩ RSENSE, but can I use a 0.5mΩ RSENSE instead?

Thanks!

  • 0
    TI__Guru 52115 points

    Hello Lin,

    From an IC perspective, I don't believe so. It is rather dependent on the FET and the amount of time that it takes for the IC to turn off the charge pump.

    We suggest in your circuit to measure how quickly the CHG and DSG pins turn off the VGS of the FETs. When the SRN and SRP lines trip the protection, the time it takes to drive the FETs off will impact the 400 A/1 ms spec you listed here. For example, if it takes the chip 10 milliseconds to turn off the CHG and DSG FETs, then it means the FETs need to sustain 4000 A of current. The trade off would be using multiple FETs in parallel with a lower gate capacitance.

    Regarding the sense register, I would suggest you follow our recommendation.

    Andy