I'm using AD7689 with internal reference 2.5V. I connected to the REF op-amp buffer to provide voltage reference to RTD current source. RTD circuit has low pass filter. My question is: What can I do to turn on ADC voltage reference before the sampling? Is it possible? Maybe something another way? I turn on the ADC power supply 10s before sampling but 2.5V reference is available only during sampling. This time is too short to stabilize RTD circuit output.