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TPS25980: destroyed upon hot plug of 24 V input power

User8905
Prodigy 10 points
Part Number: TPS25980
We are using this part to switch power to an attached strip of lights. Our input power is supplied by a MeanWell LRS-350-24 switch mode supply, which provides 24 V DC, with a max of about 15 amps, when fed from a 120 V AC source. When we have our circuit connected to the power supply and power up the supply as normal (connecting it to mains AC) we have no issue. When we hot plug this circuit into our already-powered supply, we are popping / destroying the TPS25980 chip.
We do not have TVS diodes or extra capacitors on the input or output sides of this circuit, and believe that may be the cause of the issue, but wanted to get some better understanding of the problem and possible solution before making any more changes.
  • 0 in reply to User8905
    TI__Guru** 103766 points

    Hi,

    Welcome to E2E!

    Your observation is correct. During hot-plug, there will be huge ringing on the VIN and can exceed the abs max rating of eFuse.

    Please place 100nF and TVS diode SMCJ24A-TR at the input and test again.

    BR,

    Rakesh

  • 0 in reply to Rakesh
    Prodigy 10 points

    We also have a TPS25980EVM board that we were testing as well. I modified the board, replacing the TPS259804ONRGET with the TPS259807ONRGER and adjusting the resistor divider on EN/UVLO to handle a higher voltage input. 

    I then started removing protection components from the EVM board and testing hot plug performance until I got a failure. I removed one component at a time and tested the board with 20-30 hot plug events on each component removal. The components were removed in the following order:

    D2, C3, D1, Q1, C2

    It was the removal of C2 that finally killed it. The TPS part was ruined on the 2nd hot plug event after removing C2.

    I'm just trying to understand if diodes and caps are necessary on input, output or both.

  • 0 in reply to User8905
    TI__Guru** 103766 points

    Hi,

    C1 and D1 will play major role in handling the hot-plug transients. C2 does not impact the performance.

    Can you capture Vin, Vout with respect to device ground and share the results to analyze the issue.

    Best Regards,

    Rakesh