This is a follow-up question which references to "DAC controlled LDO as current source.". I am now trying to use the recommended LTC6363-0.5 as seen in the schematics. This is a fully differential OP amp and it does not work the way I connected it to the LT3083. The OP amp does in fact produce an output voltage of 0.5 * input (DAC) voltage, but only if not connected to the LDO.
I think the problem is that the output voltage levels of "SET" and "OUT" are about a few 100mV and the LDO - in the way I need it to work - needs an output voltage level at several volts. I think the key is the VOCM input but I have no clue how to connect it correctly.
I admit I do not understand OP amps well, especially this one, as I have never seen a differential OP amp before. Is it even possible for the LTC6363 to drive the LDO as a current source or do I need a non-differential OP amp? As a side note, the latter already works for me, but I have already bought several LTC6363 and I would like to use them if possible.
Furthermore, this OP amp can only be driven with a source of +/-5.5V max and the voltage level at the 1R resistor (referenced to GND) is usually about 6..7V which seems to be a problem already.