# how to calculate PWM duty cycle for led driver

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.

• Is D3 the power led? – JonRB Jan 2 '15 at 12:33

              ON current * ON time / total pulse width time