ADC912A

Obsolete

CMOS Microprocessor-Compatible 12-Bit A/D Converter

Data Sheet (Rev. B) Product Selection Table

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Overview

Low Cost
Low Transition Noise between Code
12-Bit Accurate
±1/2 LSB Nonlinearity Error over Temperature
No Missing Codes At All Temperatures
10µ Conversion Time
Internal or External Clock

8- or 16-Bit Data Bus Compatible
Improved ESD Resistant Design
Latchup Resistant
Epi-CMOS Processing
Low 95 mW Power Consumption
Space-Saving 24-Lead 0.3" DIP,
or 24-Lead SOIC

The ADC912A is a monolithic 12-bit accurate CMOS A/D converter. It contains a complete successive-approximation A/D converter built with a high-accuracy D/A converter, a precision bipolar transistor high-speed comparator, and successive-approximation logic including three-state bus interface for logic compatibility.

The accuracy of the ADC912A results from the addition of precision bipolar transistors to Analog Devices' advanced-oxide isolated silicon-gate CMOS process. Particular attention was paid to the reduction of transition noise between adjacent codes achieving a 1/6 LSB uncertainty. The low noise design produces the same digital output for dc analog inputs not located at a transition voltage. NPN digital output transistors provide excellent bus interface timing, 125 ns access and bus disconnect time which results in faster data transfer without the need for wait states. An external 1.25 MHz clock provides a 10 µs conversion time.

In stand-alone applications, an internal clock can be used with external crystal.

An external negative five-volt reference sets the 0 V to 10 V input range. Plus 5 V and minus 12 V power supplies result in 95 mW of total power consumption.