i have implemented DAC controlled DC voltage source. I'm having trouble understanding physical reasons for voltage error due to load resistance change.
My circuit desing was taken from DAC manufacturer's datasheet ( http://www.ti.com/lit/ds/symlink/dac8811.pdf )
Here is schematics i use in my design (The load is grounded and connected to Vout pin of the amplifier) This scheme works fine with arbitrary high load resistance values (i have tested it particularly on 1 MOhm load) but when load resistances get lower (50 or 75 Ohm) i get some transfer coefficient, which is diffrent for diffrent load.
So my question is - what are the reasons for this transfer coefficient to arise? And is there any ways i can change this schematic in order for it to work fine for any load resistance value?