This application note discusses voltage references for use with Crystal Semiconductor’s successive approximation series of A/D converters. Reference design considerations, a design example and suggested reference circuits are explained in detail. Voltage references provide accurate voltages for use in data acquisition systems in order to establish a basis for conversion. In a data acquisition system, the value of the reference sets the gain of the A/D stage since the digital output corresponds to the ratio of the analog input signal to the reference voltage.