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trying to find a low-power regulator

I have a circuit that calls for a constant current sink. The LM317 would be perfect, but it requires about 5 milliamps to operate. It's too much for my battery-operated circuit to drain 5 mA all the time. So I'm looking for a 1.2 volt three-terminal series regulator like the LM317 that can run on lower current. 100 uA would fit the budget. I remember a thread some time ago on sci.electronics.design where somebody mentioned a three terminal negative regulator (pretty sure it was Joerg) that can run on microamps. Might have actually been a 2.5 volt regulator, don't remember. I even remember looking up the datasheet, but I can't remember the part number. I spent some time slogging through the parametric parts search on digikey but didn't find it. I came here to see if anybody knows the part.

Reply to
gearhead
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I don't know what was discussed earlier, but look at the LP2951. It has more than 3 terminals.

Also consider other ways of building a constant current sink, such as a suitably biased transistor or a constant-current diode.

Reply to
mc

Starting to remember now. It wasn't a negative series regulator Joerg mentioned; it was a shunt refernce, LM385. I think what I have to do is make the current sink using a low-power shunt like the tlv431 or lmv431 and a transistor. But if anybody can think of a low-power three-terminal regulator (either positive or negative), give a shout. Thanks

Reply to
gearhead

I thought of another one -- LM1117T-ADJ. There are also fixed-voltage versions.

Reply to
mc

That brings up another thing. I was wondering if it's possible to build a current sink using discretes that has a temperature coefficient as negligible as they get with band gap IC's. I incline toward thinking no. So anyway, as I mentioned in the post I put up before I saw yours, I can do the same thing with a three-terminal shunt IC and a transistor and get flat temperature response. So I'm in pretty good shape, I can build my circuit. Thanks a lot, and have a Merry Christmas!

Reply to
gearhead

Those work really well.........

Reply to
TT_Man

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