AD7794/AD7795

Rev. D | Page 2 of 36

TABLE OF CONTENTS

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

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

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

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

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

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

Timing Characteristics..................................................................... 8

Timing Diagrams.............................................................................. 9

Absolute Maximum Ratings.......................................................... 10

ESD Caution................................................................................ 10

Pin Configuration and Function Descriptions........................... 11

RMS Noise and Resolution Specifications .................................. 13

Chop Enabled.............................................................................. 13

Chop Disabled ............................................................................ 15

Typical Performance Characteristics ........................................... 16

On-Chip Registers .......................................................................... 17

Communications Register......................................................... 17

Status Register ............................................................................. 18

Mode Register ............................................................................. 19

Configuration Register .............................................................. 22

Data Register ............................................................................... 24

ID Register................................................................................... 24

IO Register................................................................................... 24

Offset Register............................................................................. 25

Full-Scale Register...................................................................... 25

ADC Circuit Information.............................................................. 26

Overview ..................................................................................... 26

Digital Interface.......................................................................... 28

Circuit Description......................................................................... 31

Analog Input Channel ............................................................... 31

Instrumentation Amplifier........................................................ 31

Bipolar/Unipolar Configuration .............................................. 31

Data Output Coding .................................................................. 32

Burnout Currents ....................................................................... 32

Excitation Currents .................................................................... 32

Bias Voltage Generator .............................................................. 32

Reference ..................................................................................... 32

Reference Detect......................................................................... 33

Reset ............................................................................................. 33

AVDD Monitor ............................................................................. 33

Calibration................................................................................... 33

Grounding and Layout .............................................................. 34

Applications Information .............................................................. 35

Flowmeter.................................................................................... 35

Outline Dimensions ....................................................................... 36

Ordering Guide .......................................................................... 36

REVISION HISTORY

3/07—Rev. C to Rev. D

Changes to Specifications Endnote 1............................................. 7

Changes to Status Register Section .............................................. 18

Changes to Ordering Guide .......................................................... 36

10/06—Rev. B to Rev. C

Updated Format..................................................................Universal

Added AD7794 C-Grade Part...........................................Universal

Changes to Specifications ................................................................ 3

Changes to Ordering Guide .......................................................... 36

6/06—Rev. A to Rev. B

Added AD7795 ...................................................................Universal

Changes to Features.......................................................................... 1

Changes to Table 1............................................................................ 3

Changes to RMS Noise and Resolution

Specifications Section..................................................................... 12

Changes to Table 19........................................................................ 20

Changes to ADC Circuit Information Section ........................... 25

Changes to Ordering Guide .......................................................... 35

4/05—Rev. 0 to Rev. A

Changes to Absolute Maximum Ratings........................................9

Changes to Figure 21...................................................................... 25

Changes to Data Output Coding Section.................................... 28

Changes to Calibration Section .................................................... 30

Changes to Ordering Guide .......................................................... 33

10/04—Revision 0: Initial Version