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TPS2491: Can't start if load is connected before switching on power

Bogdan Patlun
Prodigy 30 points
Part Number: TPS2491

Hello,

We have an issue regarding TPS2491 hot swap controller.

Apparantly, it works when the load connected after the TPS2491 is ON. E.g. connecting load on hot.

If the device has no power, we connect the load, then start everything, TPS2491 can't start-up and power the load (chunks) with a switching noize.
If we disconnect load, and then connect it again - the load powers up properly.

There seems to be an issue just when starting everything on with the load connected in prior.

Thanks!

  • 0
    TI__Expert 5940 points

    Bogdan,

    Use the power calculator tool located on the product page and also at www.ti.com/hotswap landing page.  Tutorial videos are also on the landing page.  Load should not be applied until Vout has stabilized at its normal level, using PG to enable downstream loads.  Most likely, the additional load is tripping Plim and the circuit is simply timing out.  Any load other than normal Cout dv_dt current greatly stresses the FET and risks activing the Plim timer or perhaps even taking charge current from the normal Vout rise on the Cout, prolonging power up time and hence timeout if you are using Plim power up to begin with.

    Brian