about digital power supply

[joechen]

Dear all
During these days ,I use LT2619 14bit DAC,and it works well
. the precision is 1mv .
The vref of LT2619 is 3.3v. output voltage from 0v to 3.3v .

Now I get trouble, I use TI INA118 (instrumnent opa) to
make up non-inverting amplifier .Gain=10.
But the output voltage is not accurate enough. the error is
40mv~60mv. I am worry about if I change to high power opa
like LM675....maybe gets more non-accurate.....

ex: DAC out=0.4998v OPA out=4.954v
DAC out=0.9989v OPA out=9.947v

Could someone give me a suggestion or idea . thank you~


another application,Could I use dac to adjust LM317 output
voltage?

 

[wine&dine]

>DAC out=0.4998v OPA out=4.954v
>DAC out=0.9989v OPA out=9.947v

That's an amplification factor of 10.004 and a constant -46mv offset.
Funny - I just gave another guy here a link to is five minutes ago:

http://www.analog.com/library/analogDialogue/archives/39-05/op_amp_applications_handbook.html
Chapter 1 page 57.