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TL4242-Q1: Using the TL4242 at low currents

Philip Hodgson23
Prodigy 250 points
Part Number: TL4242-Q1

The datasheet says the current setting equation applies between 0.39 and 10R, but doesn't specify a minimum output current. I would like to use this part to run a string of LEDs at 35mA, which requires a 22R reference resistor (using the equation). Is there a problem with low currents on this device, or does the equation to calculate the reference resistor get more complicated?

  • 0
    TI__Expert 5475 points
    Hi Philip,

    To get the output current of 35mA, the reference resistor required is 177mV/35mA, which is 5ohm and is within the resistance range. Would you mind checking your calculation?
    BTW, if you need to drive LED at 35mA, we have a new family of single channel LED drivers available, TPS92610/1/2-Q1. You can also check if it is suitable for your application. Thanks.

    Best regards,
    Shirley He
  • 0 in reply to Shirley He
    Prodigy 250 points
    Thanks Shirley,

    You're right. I think I must have pressed the wrong button on my slide rule!

    I've had a look at the TPS92611, and it looks like this might be better than the TPS4242 - having the LEDs connected to a common ground will simplify the tracking, and the board area used by the devices are about the same.

    Regards

    Phil