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TPS1HB08-Q1: About TPS1HB08-Q1 Current Limit and Thermal Shutdown

GARAM AN
Intellectual 1950 points
Part Number: TPS1HB08-Q1

Hello all,

I could find current limit at 70A and thermal shutdown at 150 degree.

When I calculate Junction temp with instruction on the datasheet,

Tj = Temp + 32.6 * I * I * Ron

    = 25 + 32.6 * 20 * 20 * 8m

    = 170

When peak current is 20A, Junction Temp is over than shutdown limit.

Cannot the current be over than 20A? 

  • 0
    TI__Mastermind 22240 points

    Hi,

    The thermal value RθJA is based on DC values. You mentioned that you were calculating with peak current which may give you inaccurate values for seeing if the operation is valid on the device. So it is correct that if you kept it at 20A, the device would shut off unless the 20A is for a short duration as in the case of inrush currents or short-to-ground which is what allows the device to have high current limits such as 70A.

    We also recommend using the max RON value when looking at calculating junction temperature (which in the TPS1HB08-Q1’s case is 16-mOhm)

  • 0 in reply to Anthony P Pham
    TI__Intellectual 1950 points

    So, when I recalculate this,

    1. At temp=25

    Tj = Temp + 32.6 * I * I * Ron

        = 25 + 32.6 * 15 * 15 * 16m

        = 142

    The limit that device do not shut off is when current I = 15A?

    2. At temp=70

    Tj = Temp + 32.6 * I * I * Ron

        = 70 + 32.6 * 12 * 12 * 16m

        = 145

    The limit that device do not shut off is when current I = 12A?

    Are those correct?

    Thank you

  • 0 in reply to GARAM AN
    TI__Mastermind 22240 points

    Hi, 

    Yes, these would be correct (I calculated about 15.48A at 25C and 12.38A at 70C) assuming that these are will be your steady state current loads.