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Original question:

TPS92641: TPS92641 Schematic review.

TPS92641: adjustable current source design

Bruce li
Genius 5580 points
Part Number: TPS92641
Other Parts Discussed in Thread: TPS92640

Dear TI Experts,

My customer want to design an adjustable current source, current  range from100mA to 10A,  accuracy from 1ma to 5ma. They have tried TPS92641 but failed. Could you kindly give some advices for such application? Is there any better choice? Thanks a lot.

  • 0
    TI__Mastermind 28655 points

    Hello,

    1 mA/100 mA = 1% accuracy

    5 mA/10A = 0.05% accuracy

    To do this you will need very accurate external circuit and current sense.  We have no parts that are this accurate, however some of them could be with and external current sense and current regulation loop if designed correct.  Is there a reason for this accuracy?

    Best Regards,

  • 0 in reply to Irwin Nederbragt
    Genius 5580 points

    Dear Irwin,

    thanks for your reply, customer need to build an adjustable current source into their product to measure some key parameters.

    What's the best accuracy out of all LED driver devices, and what's ths accuacy? Could you kindly give some advices? Thanks a lot.

  • 0 in reply to Bruce li
    TI__Mastermind 28655 points

    Hello Bruce,

    The TPS92640/TPS92641 are probably a good choice.  The error amplifier input offset is +/- 600 uA with a maximum input set-point of 2.54V/10 = 0.254V.

    Accuracy depends on many things such as temperature range, component tolerances, input voltage range, output voltage range, switching frequency PCB routing, etc.

    For example choosing a current sense resistor that has a +/- 1% tolerance will add that error to the overall set-point.

    May I ask what you are trying to accomplish and the need for such accurate of a set-point?

    Best Regards,

  • 0 in reply to Irwin Nederbragt
    Genius 5580 points

    Dear Irwin,

    Thanks a lot for your support, customer need such accurate to accomplish a test function for battery and BMS board.

  • 0 in reply to Bruce li
    TI__Mastermind 28655 points

    Hello Bruce,

    Two ways to do this are to use a part, such as the TPS92640/TPS92641 and measure the output current accurately.  If it is off use the adjust to get it where you want.

    The other would be to have external circuitry as the control loop for the current.  This would close the loop around an accurate current measurement and adjust the TPS92640/TPS92641.

    These will only be as accurate as the current measurement and associated circuitry.

    Best Regards,

  • 0 in reply to Irwin Nederbragt
    Genius 5580 points

    Dear Irwin,

    Got it, thanks a lot for your help