Digital Current Control for LED array
- From: allthekings_horses@xxxxxxxxxxx
- Date: 19 Dec 2005 13:35:05 -0800
I'm very new to most concepts of electronics and I need some advice.
Please keep anwers in laymans terms otherwise I'll get lost. thanks
I'm looking to power arrays of 7 LEDs with a digital current control
system. I want to be able to write a program that can control the
irradiance of the LED arrays. The problem is that the irradiance of
all 7 LEDs needs to be matched, so while one LED will be taking 1amp
another is only taking 0.8amps another 0.9 etc so they give off the
exact same amount of light. I'm not sure if I need to produce a
current limiting circuit for each LED that is digitally controlled or
if I can have one large supply that is digitally controlled that feed
the 7 LEDs in parallel.
A 7amp supply fed to 7 LEDs in parallel would produce 1 amp at each
LED. If I put a circuit in front of each LED which supplies it with a
percentage of that current (say 90% giving a curent to the LED of
0.9amps) then I can supply 0.7amps from the supply (0.1 amp to each
LED) and still get 90% of the current at the LED (0.09amps) then I've
cracked it. The relationship between irradiance and current on the
LEDs I've got is effectively linear so an LED that requires 90% of the
current to produce the same irradiance as another LED will require 90%
whether that's at 0.1 amp or 1amp.
Any ideas??
Thanks
Evan
.
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