The AD574AJNZ is a complete 12-bit successive-approximation Analog-to-digital Converter (ADC) with 3-state output buffer circuitry for direct interface to a 8 or 16-bit microprocessor bus. A high precision voltage reference and clock are included on-chip and the circuit guarantees full-rated performance without external circuitry or clock signals. The AD574A design is implemented using analog devices bipolar/I²L process and integrates all analog and digital functions on one chip. Offset, linearity and scaling errors are minimized by active laser-trimming of thin-film resistors at the wafer stage. The voltage reference uses an implanted buried Zener for low noise and low drift. On the digital side, I²L logic is used for the successive-approximation register, control circuitry and 3-state output buffers.