ADC08031CIWM datasheet(10/24 Pages) NSC

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ADC08038 Functional Block Diagram

Functional Description

1.0 MULTIPLEXER ADDRESSING

The design of these converters utilizes a comparator struc-

ture with built-in sample-and-hold which provides for a differ-

ential analog input to be converted by a successive-

approximation routine.

The actual voltage converted is always the difference be-

tween an assigned “+” input terminal and a “−” input terminal.

The polarity of each input terminal of the pair indicates which

line the converter expects to be the most positive. If the as-

signed “+” input voltage is less than the “−” input voltage the

converter responds with an all zeros output code.

A unique input multiplexing scheme has been utilized to pro-

vide multiple analog channels with software-configurable

single-ended, differential, or pseudo-differential (which will

convert the difference between the voltage at any analog in-

put and a common terminal) operation. The analog signal

conditioning required in transducer-based data acquisition

systems is significantly simplified with this type of input flex-

ibility. One converter package can now handle ground refer-

enced inputs and true differential inputs as well as signals

with some arbitrary reference voltage.

A particular input configuration is assigned during the MUX

addressing sequence, prior to the start of a conversion. The

MUX address selects which of the analog inputs are to be

ADC08031CIWM 数据表(PDF) 10 Page - National Semiconductor (TI)