Electrical – How significant is 16bit in 16bit PWM resolution?

brightnessled-driverpwm

Is there any significance other than the granularity of duty cycle levels?. I'm working on an led driver where the light output levels should be very smooth while dimming. There will be 254 levels of brightness. if it is just about brightness levels a 10bit PMW is enough, isn't it?. Is there something to do with PWM frequency and resolution considering the flickering of led.
Any help would be very much appreciated.

Thanks

Best Answer

Trying to find the real question in your question, which is a bit unclear...

Is there something to do with PWM frequency and resolution considering the flickering of led.

PWM frequency is important: below a few hundred Hz, it will flicker, and this is unpleasant. But above this, your ceramic capacitors can whine, which is also annoying.

So, 25kHz is a good PWM frequency. Capacitor noise is inaudible, and it sure won't flicker. With 8-bit PWM this gives a minimum clock frequency of 6.4 MHz.

If your micro has a 8MHz clock and a 8-bit timer, then there is no problem, except if you want to allow very low light output.

If your LED puts out, say 256 lumen... then with the PWM at 1/256 duty cycle it still outputs one lumen. If you want lower, you'll have to use a PWM with more bits.

Note that PWM is not the only way to dim a LED. You can also control the current directly, if the driver allows this. This can be more efficient, but light output does not vary linearly with current.