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TLC5941: output current vs output voltage

Howard Zou
Genius 12365 points
Part Number: TLC5941

In the datasheet we have the figure of OUTPUT CURRENT vs OUTPUT VOLTAGE.

My customer configure OUT0 current to be 60mA, and OUT0 is connected to an LED, according to the plot, as long as the voltage of OUT0 is higher than 0.7V, the current should be almost constant.

I wonder what's the accuracy of the turning point? Is it possible that some device's turning point is 0.7V for 60mA, while other device turning point is 1V for 60mA?

I guess the figure below is just for typical characteristics.

  • 0
    TI__Genius 12915 points

    Hi Howard,

    Here is no spec to indicate accuracy of knee voltage. Normally we recommend customer left enough knee voltage margin to prevent potential VLED ripple or difference between channels, while above 1V should be OK. What value of VLED power line and forward voltage of the LED when Iout=60mA customer used? 

  • 0 in reply to Hardy Wu
    TI__Genius 12365 points

    Hardy,

    thanks. We have different LEDs, and we will have 0.6V, 0.8V and 1.1V on OUT pin. While all the LEDs will have brightness variation after tens of hours work.

    So I ask the question about knee voltage.

    If the voltage is below knee voltage, the variation of forward voltage of LED (even small) may cause large current variation.

    But if the voltage is above knee voltage, I think the variation of forward voltage of LED should be neglectable.