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TPS2HB35-Q1: thermal shutdown questions

Sherry Liang
Genius 10255 points
Part Number: TPS2HB35-Q1

Dear team,

Could you please help clarify the definition of TJ,FET and TJ,controller? In my understanding, TJ,FET is the junction temp of TPS2HB35-Q1, then what is the TJ,controller?

Fo rthe second picture, Tj means TJ,FET in my understanding, then what is the relationship between TA and TJ,controller?

Thanks & Best Regards,

Sherry

  • +1
    TI__Mastermind 32650 points

    Hi Sherry,

    There are two regions that are monitored within the device. This is the FET and the controller of the device. This is done so to provide addition protection in the event of a large power dissipation across the fet of the device. In this situation (like a short to GND), the temperature of the FET heats up much faster than the rest of the device as it takes some time for heat to propagate. In order to avoid damage or degradation cause by this hotspot, the device makes sure that if the FET temperature is hotter than the controller temperature by tREL, then the device shuts down. This is known as relative thermal shutdown. It allows the heat to propagate and avoids the formation of hotspots in the device.

    In the second case, the assumption is that the controller is still at the ambient temperature. This is just to show an extreme case for explanation of the current limiting behavior.

    Thanks,

    Shreyas