The primary purpose of a voltage reference (VREF) is to establish system accuracy. An analog-to-digital converter (ADC), for example, uses a reference voltage to set its full-scale input level. This application note explains how a tradeoff between initial accuracy and temperature coefficient (tempco) can broaden your selection of voltage references while meeting a given requirement for system accuracy. The calculations presented determine precisely the tempco needed for a given value of initial accuracy, and vice versa.