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Which chip fits best

Gerhard Kreuzer
Expert 2580 points
Other Parts Discussed in Thread: INA168, INA195, INA139

Hi,

my situation:

SMPS, switching frequency <120khz, Vin <30V, Ipeak 17A, I Need a current Monitor for current mode Regulation, so 17A ==> 1.3V.

Which chip fits?

Thanks a lot.

With best regards

Gerhard

  • 0
    TI__Genius 14825 points

    Gerhard,

    Thanks for your question, we'll review your requirements and make some suggestions Tuesday.

    Best regards,

    Jason Bridgmon

  • 0
    TI__Intellectual 1385 points

    Hello Gerhard,

    The INA168 and INA195 I think will be the best fit.

    Regards,

    Jamieson Wardall

  • 0 in reply to Jamieson Wardall
    Expert 2580 points

    Hi Jamieson,

    INA168 .. 800kHz GBW so with G=10 I am down at 80kHz. f Switch is 75kHz and so I think this is quite too low. As the Peak current is 17A, I have to use a small resistor.

    INA 195, GBW also too small and I also Need a seperate supply (Vcc max 18V).

    I Need the sensor for Peak current control Loop, so the shape of the inductor current has to be reproduced correct!!!

    I ended up with INA139, 4MHz GBW, supply as high as 36V, I have 30V max. I do some Simulation and  it Looks fine. Only drawback  I have to Limit the gain of the INA139 and use an OP amp to amplifiy the Signal to the needed Level.

    Is there a simpler solution?

    With best regards

    Gerhard

  • 0 in reply to Gerhard Kreuzer
    TI__Intellectual 1385 points

    Hi Gerhard,

    For a component level power supply I think this is the simplest design for the switching frequency you desire.  This the highest GBW solution.  You are correct, having 10x the switching frequency to catch the peak current.

    Regards,

    Jamieson Wardall