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LM1085 constant current regulator not working. Please help!

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isaac12345

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Hi,

I tried to wire up the lm1085-adj, as below, as a constant current source(230mA) for charging a battery pack of NiMH cells. Unfortunately, its not working for some reason and I cant seem to figure it out. I think I'm missing something very simple. Please help.
 

Re: LM1085 constant current regulator not working. Please he

The output of the circuit is on the ADJ pin and not on the OUT pin. So, just move the battery to the ADJ pin. The current will be I = 1.25/R
 

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    isaac12345

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Re: LM1085 constant current regulator not working. Please he

It worked!! Thanks a ton!
That was quite odd because I thought , like the LM317T, I would need to connect the battery pack to the output pin.

Is it mentioned somewhere in the datasheet?
 

Re: LM1085 constant current regulator not working. Please he

isaac12345 said:
That was quite odd because I thought , like the LM317T, I would need to connect the battery pack to the output pin.
Click to expand...

With the LM317 the load should also be connected to the ADJ pin, not the OUT pin.

See the diagram at the bottom of page 21:

www.national.com/ds/LM/LM117.pdf

Keith.
 

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