Disclosed is a circuit for controlling the temperature and the bias voltage of a detector used by an X-ray analytical instrument. The circuit uses a single common reference voltage for the temperature measurement and for all the ADCs and DACs in the circuit, resulting in reduced drift and improved reproducibility of detector temperature and bias voltage. ADCs with a larger number of bits are used to produce precision values of the temperature, the bias voltage, and their respective setpoints. The setpoints are digitally varied until the precision setpoint values correspond to desired values of temperature and bias setpoints.