The way to do it in hardware fully is to output an analog voltage and run that voltage through a logrithmic V-I converter to drive an led.A V-I converter can be an opamp; but the simplest would be to utilize a transistor's b-e junction non-linearity. Simple as that.
Hi dhenry.Can you point me towards any example circuits that show how to 'utilize a transistor's b-e junction non-linearity' in this way? Also how do you work out the curve that a particular transistor would give you?Btw, I plant use this if possible in two scenarios - One is pwm source > non linear correction > mosfet (to control 12 led strip)The other is pwm source > non linear correction > transistor + constant current source (to control a single hight power led)Do you think your example can integrate with both these systems?Many thanks
I was just thinking about the implications of not having pwm anymore.
On the other hand, you could use a DAC. These usually have a voltage output and you could use that as the input to a linear I-V converter.Similar restrictions as above apply, however. The ratio between drive current and light output also is not linear, so now you really have to do some math That's just another neat idea. Of course
Do you know of any drivers or pwm generators that are similar to the ws2801? Ie can be daisy chained on the spi bus or similar? I really like how modular and expandable these chips are.