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.