AD7785

Rev. 0 | Page 2 of 32

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications....................................................................................... 1

General Description ......................................................................... 1

Functional Block Diagram .............................................................. 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

Timing Characteristics..................................................................... 6

Timing Diagrams.......................................................................... 7

Absolute Maximum Ratings............................................................ 8

ESD Caution.................................................................................. 8

Pin Configuration and Function Descriptions............................. 9

Output Noise and Resolution Specifications .............................. 11

External Reference...................................................................... 11

Internal Reference ...................................................................... 12

Typical Performance Characteristics ........................................... 13

On-Chip Registers .......................................................................... 14

Communications Register......................................................... 14

Status Register ............................................................................. 15

Mode Register ............................................................................. 15

Configuration Register .............................................................. 17

Data Register ............................................................................... 18

ID Register................................................................................... 18

IO Register................................................................................... 18

Offset Register ............................................................................ 19

Full-Scale Register...................................................................... 19

ADC Circuit Information.............................................................. 20

Overview ..................................................................................... 20

Digital Interface.......................................................................... 21

Circuit Description......................................................................... 25

Analog Input Channel ............................................................... 25

Instrumentation Amplifier........................................................ 25

Bipolar/Unipolar Configuration .............................................. 25

Data Output Coding .................................................................. 25

Burnout Currents ....................................................................... 26

Excitation Currents .................................................................... 26

Bias Voltage Generator .............................................................. 26

Reference ..................................................................................... 26

Reset ............................................................................................. 26

AVDD Monitor ............................................................................. 27

Calibration................................................................................... 27

Grounding and Layout .............................................................. 27

Applications Information .............................................................. 29

Temperature Measurement using a Thermocouple............... 29

Temperature Measurement using an RTD.............................. 30

Outline Dimensions ....................................................................... 31

Ordering Guide .......................................................................... 31

REVISION HISTORY

4/07—Revision 0: Initial Version