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TPS40422: temperature sensor layout

Alberto Doronzo
Expert 4420 points
Part Number: TPS40422

Hi,

In the datasheet for TPS40422, both the layout recommendations and the schematic notes (pages 24 and 62) suggest to place the temperature sense BJTs close to the Inductor.

What is the reason for choosing the inductor instead of the FETs by instance? - I imagine the answer is that it depends on the design, but I wanted to make sure.

Thank you!

Regards,

Alberto

  • 0
    TI__Mastermind 24075 points
    Hi Alberto,

    TPS40422 use inductor DCR for current sense. The inductor DCR changes with temperature. The temperature sensed will be used for temperature compensation on current readout. That's why we suggest to place sense BJT close to inductor.

    Here is the suggestion, place BJT close to inductor, but add ground copper between BJT and inductor to shield noise.
    Use seperate ground trace as return trace.
    Add a bypass capacitor next to BJT.

    Thanks
    Qian