Controllable LED Driver Design

Thread Starter

arman74

Joined Jul 1, 2017
43
You can use Pulse Width Modulation and suitable power FET devices and a single current sense resistor for each of the series strings, and then you are not going to need to design any analog control circuits. Just set the voltage for each string at a level that gives about 90% of max output at 100% on time. Then you can do it all in software.Just use a high enough PWM frequency to avoid visible flicker. AND heat-sink those series switch transistors. Probably the cheapest, easiest, most compact way of doing it.
upload_2019-6-17_16-15-39.png

I think that this circuit works.I just wanted to know if there is any other better circuits.
 

MisterBill2

Joined Jan 23, 2018
9,266
I was thinking that the voltage across the current sense resistor would be amplified, possibly, and fed to an analog input so that there would be feedback available to assist in setting the desired LED current. In the circuit shown the power source for the driver will need to be a high enough voltage to switch the FET on fully. With the 36 volt source available that should be a simple matter. AND there are driver ICs available, but I have not used them and so others will need to comment on that. But the PWM application part exactly matches my suggestion.
 
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