ADC Single SAR 8-bit Parallel 20-Pin PDIP Rail

The ADC0803 and ADC0805 are CMOS 8-bit, successive-approximation, analog-to-digital converters that use a modified potentiometric (256R) ladder. These devices are designed to operate from common microprocessor control buses with the 3-state output latches driving the data bus. The devices can be made to appear to the microprocessor as a memory location or an I/O port. Detailed information on interfacing to most popular microprocessors is readily available from the factory. A differential analog voltage input allows increased common-mode rejection and offset of the zero-input analog voltage value. Although a reference input (REF/2) is available to allow 8-bit conversion over smaller analog voltage spans or to make use of an external reference, ratiometric conversion is possible with the REF/2 input open. Without an external reference, the conversion takes place over a span from VCC to ANLG GND. The devices can operate with an external clock signal or with an additional resistor and capacitor, using an on-chip clock generator. The ADC0803C and ADC0805C are characterized for operation from 0°C to 70°C. The ADC0803I and ADC0805I are characterized for operation from -40°C to 85°C.

8-Bit Resolution

Ratiometric Conversion

100-us Conversion Time

135-ns Access Time

Guaranteed Monotonicity

High Reference Ladder Impedance 8 kO Typical

No Zero Adjust Requirement

On-Chip Clock Generator

Single 5-V Power Supply

Operates With Microprocessor or as Stand-Alone

Designed to Be interchangeable With National Semiconductor and Signetics ADC0803 and ADC0805