> As far as driving goes, LEDs are specified at rated current and
> voltage will vary. You can "bin" them - ie sort for similar voltage
> drop at a given current - but this is a poor compromise. The "proper"
> method is to control current. How tightly you need to control current
> depends on your need for consistent brightness across LEDs and how
> well matched the LEDs are for brightness. I know how good the latter
> is likely to be if you source them from the torches that you describe
> :-).


I've designed some dental curing lights using a boost converter off a
lithium ion battery and using a current sense amplifier for feedback. As
pointed out above, the LED voltage does vary. Something I've wondered
about is doing power regulation instead of current regulation. It seems
that this would result in more consistent light output and dissipation
than using just current regulation. It, of course, would be a bit more
complicated and perhaps not worth the effort. Has anyone done V*I
regulation of LEDs?

Harold

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