The AD7572 is a complete, 12-bit ADC that offers high speed performance combined with low, CMOS power levels. The AD7572 uses an accurate, high speed DAC and comparator in a successive-approximation loop to achieve a fast conversion time. An on-chip, buried Zener diode provides a stable reference voltage to give low drift performance over the full temperature range and the specified accuracy is achieved without any user trims. An on-chip clock circuit is provided, which may be used with a crystal for stand-alone operation, or the clock input may be driven from a external clock source such as a divided-down microprocessor clock. The only other external components required for basic operation of the AD7572 are decoupling capacitors for the supply voltages and reference output.