Dear Analog Devices Technical Support Team,
I am designing a voltage-controlled voltage source using the LT30800EQ, where the output voltage is controlled by a DAC connected to the SET pin.
However, I am observing an unexpected behavior when commanding the DAC to output low voltages. In some cases, when the DAC is set to 0 V, the output does not return to 0 V as expected and instead remains at approximately 3.3–4.2 V. Interestingly, the DAC appears to operate normally when commanded to output voltages above this range.
I have also noticed that, on occasion, the DAC can successfully return to 0 V after first being set to a voltage above the 3.3–4.2 V range. This behavior is intermittent and difficult to reproduce consistently.
Could you please advise whether there are any considerations, limitations, or design issues related to driving the LT3080 SET pin directly from a DAC that might explain this behavior? Have I overlooked anything in the implementation?
I have attached the schematic for reference.
