Harold Hallikainen wrote...

>I'm loooking for a two terminal constant current device that could be put
>between an LED and a variable DC supply to hold the LED current at 5mA as
>the supply varies over a 0-10V range (recognizing we're not going to get
>it at 0V, but I'd like the widest range possible). So far i've found the
>Central Semiconductor CCLM5750 which is a nominal 5.750mA, but it takes
>4.5V to get 80% of the rated current. Anyone have other ideas?

How about NSC's LM134?  It's actually billed as a temperature
sensor because its current output is proportional to absolute
temperature; but it seems to me that would be an advantage in
this application as it would tend to offset the LED's somewhat
negative temperature dependence.

AFAIK the LM134 requires about 1 volt of headroom to operate.  A
current programming resistor is also required; for 5 mA the value
would be about 12 ohms.

HTH...

Dave D.

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