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Can I use non peak current rated power supply for peak current application

perumal V
Prodigy 20 points

Hi,

Kindly clarify the doubt regarding power supply selection.

In our product, the 5V constant current consume is ~7A and the peak current consume is ~18.5A for 900us.

For that, I have selected  a power supply with the maximum current is 10A for 5V. It is don't have the peak current rating also.

Can i use this in our product? 

document attached for your reference.Current Measurement observation.xls

  • 0
    TI__Guru 57555 points

    900us is a long time for a current pulse.  Even with a large output capacitor the output voltage would droop.  I think in you case you may need a supply that can deliver the 18.5A.

  • 0 in reply to Frank De Stasi
    Prodigy 20 points

    Hi

    Thanks for your reply.

    Now, I'm need to prove the non-sufficient of 10A rated supply for 18.5A peak current application by calculation.

    kindly advice to calculate the average power for train of peak current (pulses).

    peak current waveform is attached for reference.

  • 0 in reply to perumal V
    TI__Guru 57555 points

    A regulator with a 10A maximum load current will have some reserve above 10A to supply the load.

    The reserve depends on the current limit, inductor value, input/output voltage and frequency. 

    If the load spike trips current limit the output voltage will fall.  The amount of output voltage dip will depend

    on the current, the time and the value of Cout.  If the load spike is within the reserve capacity then the current limit

    will not trip and the output will not droop.  You can use the following equation to estimate the maximum output current

    at the point of current limit :  Ioutmax = Icurrentlimit - 0.5*DI

    DI = (Vin-Vout)*(Vout/Vin)/(L*Fs)