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I am trying to design a constant current led driver. I know the peak and the holding current range for led driver How would I find the PWM duty cycle based on the current that I need to control?

Microcontroller is used for PWM output.

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  • \$\begingroup\$ Is D3 the power led? \$\endgroup\$ – JonRB Jan 2 '15 at 12:33
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I'm not certain that you can talk about constant current when using a PWM as the current varies during the cycle. Perhaps a better term would be an average current.

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The average current over one cycle would be:

              ON current * ON time / total pulse width time

For example if the ON current was 2A, the ON time 10uS and the total pulse width time was 100 uS, the average current would be 2*10/100 = 0.2A

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  • \$\begingroup\$ You can because there is an inductor \$\endgroup\$ – JonRB Apr 3 '15 at 20:58

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