The HI-X74(A) is a complete 12-bit, Analog-to-Digital
Converter, including a +10V reference clock, three-state
outputs and a digital interface for microprocessor control.
Successive approximation conversion is performed by two
monolithic dice housed in a 28 lead package. The bipolar
analog die features the Intersil Dielectric Isolation process,
which provides enhanced AC performance and freedom
from latch-up.
Custom design of each IC (bipolar analog and CMOS digital)
has yielded improved performance over existing versions of
this converter. The voltage comparator features high PSRR
plus a high speed current-mode latch, and provides precise
decisions down to 0.1 LSB of input overdrive. More than 2X
reduction in noise has been achieved by using current
instead of voltage for transmission of all signals between the
analog and digital ICs. Also, the clock oscillator is current
controlled for excellent stability over temperature.
The HI-X74(A) offers standard unipolar and bipolar input
ranges, laser trimmed for specified linearity, gain and offset
accuracy. The low noise buried zener reference circuit is
trimmed for minimum temperature coefficient.
Power requirements are +5V and ±12V to ±15V, with typical
dissipation of 385mW (HI-574A, HI-674A) at 12V.

Features
• Complete 12-Bit A/D Converter with Reference and Clock
• Full 8-Bit, 12-Bit or 16-Bit Microprocessor Bus Interface
• Bus Access Time . . . . . . . . . . . . . . . . . . . . . . . . . . . 150ns
• No Missing Codes Over Temperature
• Minimal Setup Time for Control Signals
• Fast Conversion Times
- HI-574A (Max) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25µs
- HI-674A (Max) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15µs
• Low Noise, via Current-Mode Signal Transmission
Between Chips
• Byte Enable/Short Cycle (AO Input)
- Guaranteed Break-Before-Make Action, Eliminating Bus
Contention During Read Operation. Latched by Start
Convert Input (To Set the Conversion Length)
• Supply Voltage . . . . . . . . . . . . . . . . . . . . . . ±12V to ±15V
• Pb-Free Available (RoHS Compliant)

Applications
• Military and Industrial Data Acquisition Systems
• Electronic Test and Scientific Instrumentation
• Process Control Systems