Description

The AD574A is a complete 12-bit successive-approximation analog-to-digital converter with 3-state output buffer circuitry for direct interface to an 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.The AD574A is available in six different grades. The AD574AJ, K, and L grades are specified for operation over the 0°C to +70°C temperature range. The AD574AS, T, and U are specified for the -55°C to +125°C range. All grades are available in a 28-pin hermetically-sealed ceramic DIP. Also, the J, K, and L grades are available in a 28-pin plastic DIP and PLCC, and the J and K grades are available in ceramic LCC.The S, T, and U grades in ceramic DIP or LCC are available with optional processing to MIL-STD-883C Class B; the T and U grades are available as JAN QPL. The Analog Devices' Military Products Databook should be consulted for details on /883B testing of the AD574A.