240VAC in, for LED driving (Dimmable)

3 posts / 0 new


I'm making a High Bright LED driver using a TOP223. I need it to be dimmable with a PWM signal. I was thinking of using a Shunt resistor to sense de LED current and compare it with the PWM signal, filtered with a simple RC filter. Is this possible? any ideas?


Laureano Pizales

Yes you can lowpass filter the PWM signal then use it as a reference for a constant-current loop. Your PSU must have a CVCC (constant voltage constant current) characteristic, wherein the CC setpoint is adjusted by the filtered PWM signal. The CV setpoint has to be slightly above the maximum anticipated LED voltage at full current.

Thanks for the quick response.