LM317T as a current regulator

nanawhite107

New member
I am trying to use LM317T as a current regulator and the setup is from its data sheet. I couldn't get it to work.

Here is the datesheet of lm317t


I want a constant output current of 10uA when input voltage is changed from 3V to 2V. Since the internal reference voltage between output and adj is 1.25V, I put a resistors of 125kohm from adj to output.

I am getting very high currents like 3mA and I can't figure out why. I appreciate all your help.
 
It's only rated for a minimum of 10mA for load regulation for a Vo of less than 5V. It's a 20W current regulator and made to handle more power than where you're operating at. What you're looking for is low power low dropout regulators or LDOs for short. I know of a few that can handle down to 100uA, but to get lower than that I'm not sure what exists. Try texas instruments or linear technologies (before analog devices merger)
 
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