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TPS61027 Issue

susan
Prodigy 20 points
Other Parts Discussed in Thread: TPS61027

Hi,

I have a question about the maximum output current of  tps61027, now the max value  I can get  is 100mA Max(Vo=5V). I wonder the selection of inductor(6.8uH,1500mA), Could you please give me some suggestion about this component and other reason that affect output current ?

Thank you so much for your time and consideration!

Susan

  • 0
    TI__Mastermind 36110 points

    The datasheet provides equations to calculate the maximum current.  These equations are valid.  One problem you might be seeing is a startup problem.  Although this IC does provide full rated current, it does not start up into a full load condition.  Real world loads don't actually pull full current at startup.  Real world loads don't behave like resistive loads at startup.  The real world load will work ok, but the resitive load may not.  Example is a real world load that pulls 1A at 5V.  This is equivalent to a 5 ohm load.  The real world load will power up and work correctly, but the IC will not startup properly into a 5 ohm load.  If you start the IC into a smaller load and let it enter regulation, THEN apply full load, the IC will work properly.

  • 0 in reply to Matthew Day
    Prodigy 20 points

    I try soft start IC, The output is 4.6V when the load is 20ohm. that's means the current  is 230mA. This value is bigger that start with load, but it still can not reach the caculated value 1A, even  500mA. but your answer is really helpful, thank you very much!