Hello
So I tried dimming LED's with PWM yesterday using my AVRmega48.
I used I/o for the PWM , and I think the that the code is irrelevant
for the following issue so i'm not going to post it .
***
The issue is that when the duty cycle approaches very small percentages (<7%) then there is a huge drop in the LED brightness and vice versa: When increasing the duty cycle from 0% upwards it turns on alot after a few percent and then progresses relatively linearly . Why is that?
I understand that our perception of brightness is non-linear , but that has nothing to do with this .
My best guess is that this has something to do with semiconductor sorcery due to the fact that at low percentage duty cycles the pulses are very short .
***
I have the LED's connected through a BJT general purpose NPN (22kohm at base) and the PWM is running at 10khz . Thing is the same issue happens without the transistor so I think the problem isn't there either .
I am using Blue smd led's with about 10ma current .
Anyone care to shed some light on this?
So I tried dimming LED's with PWM yesterday using my AVRmega48.
I used I/o for the PWM , and I think the that the code is irrelevant
for the following issue so i'm not going to post it .
***
The issue is that when the duty cycle approaches very small percentages (<7%) then there is a huge drop in the LED brightness and vice versa: When increasing the duty cycle from 0% upwards it turns on alot after a few percent and then progresses relatively linearly . Why is that?
I understand that our perception of brightness is non-linear , but that has nothing to do with this .
My best guess is that this has something to do with semiconductor sorcery due to the fact that at low percentage duty cycles the pulses are very short .
***
I have the LED's connected through a BJT general purpose NPN (22kohm at base) and the PWM is running at 10khz . Thing is the same issue happens without the transistor so I think the problem isn't there either .
I am using Blue smd led's with about 10ma current .
Anyone care to shed some light on this?