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very low voltage regulator

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Hello,

I am using a differential current-out DAC and I am connecting the outputs to an op-amp to get a single-ended output, as described in the enclosed picture.

But instead of having 2.5 V for the common-mode voltage of the op-amp, I would like to have 0.2 V.

Then what could be the simplest and more stable solution to have 0.2 V?
I tried to use a diode with a forward voltage of 0.7 V and then adding a voltage divider using resistor but as the current is changing at the output of the DAC, this reference voltage do not stay constant at 0.2 V.

If someone has a solution, I would be glad to hear it. ;-)

Thanks
 

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Looking at the circuit, if you fed your +5V down via a high value resistor to the 500 ohm series resistor to the + input, using the 500+25 ohms to form the lower arm of you potentiometer, then providing the resistor is high enough in value it might not upset your calibration too much. I chain = .2 /525 Amps therefore R = 4.8 X 525/.2 ~ 125K.
Frank
 

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Isn't obvious? Just change the 2k/2k divider respectively. The parallel circuit of both resistors has to keep a value of 1 k, the divided volttage should be 0.2V. You get nominal resistance values of 1.04k and 25k.
 

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