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LM34927: IC working status and thermal pad soldering

Sheldon He
Expert 8585 points
Part Number: LM34927

Hi expert,

My customer tested one piece of LM34927 without soldering the thermal pad. They'd like you to confirm if their IC is working normally in this condition.

They capatured voltage between A and B with a scope and get below waveform.

BTW, could you help us to know the percentage of solder coverage for this IC's thermal pad?

How much will the thermal resistance be different in this two conditons?

Thanks

  • 0
    TI__Mastermind 27045 points

    Hi Sheldon,

    The chip may work abnormally if the thermal pad is not connected to ground plane on PCB:

    1. chip has no enough capability to output power because of high thermal resistance, Theta-JA may increase from 40C/W to 110C/W.

    2. the floating thermal pad will couple noise to small signal control circuit and makes switching unstable.

    B R

    Andy