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AD7765

Rev. A | Page 2 of 32

TABLE OF CONTENTS

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

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

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

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

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

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

Timing Specifications .................................................................. 6

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

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

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

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

Typical Performance Characteristics ........................................... 11

Terminology .................................................................................... 14

Theory of Operation ...................................................................... 15

Σ-Δ Modulation and Digital Filtering ...................................... 15

AD7765 Antialias Protection .................................................... 16

AD7765 Input Structure ................................................................ 17

On-Chip Differential Amplifier ............................................... 18

Modulator Input Structure ........................................................ 19

Driving the Modulator Inputs Directly ................................... 19

AD7765 Interface ............................................................................ 20

Reading Data ............................................................................... 20

Reading Status and Other Registers ......................................... 20

Writing to the AD7765 .............................................................. 20

AD7765 Functionality ................................................................... 21

Synchronization .......................................................................... 21

Overrange Alerts ........................................................................ 21

Power Modes ............................................................................... 22

Decimation Rate Pin .................................................................. 22

Daisy Chaining ............................................................................... 23

Reading Data in Daisy-Chain Mode ....................................... 23

Writing Data in Daisy-Chain Mode ........................................ 24

Clocking the AD7765 .................................................................... 25

MCLK Jitter Requirements ....................................................... 25

Decoupling and Layout Information ........................................... 26

Supply Decoupling ..................................................................... 26

Reference Voltage Filtering ....................................................... 26

Differential Amplifier Components ........................................ 26

Layout Considerations ............................................................... 26

Using the AD7765 ...................................................................... 27

Bias Resistor Selection ............................................................... 27

AD7765 Registers ........................................................................... 28

Control Register ......................................................................... 28

Status Register ............................................................................. 28

Gain Register—Address 0x0004 ............................................... 29

Overrange Register—Address 0x0005 ..................................... 29

Outline Dimensions ....................................................................... 30

Ordering Guide .......................................................................... 30

REVISION HISTORY

8/09—Rev. 0 to Rev. A

Changes to Table 3 ............................................................................ 6

Changes to Table 4 ............................................................................ 8

Changes to Σ-Δ Modulation and Digital Filtering Section ....... 15

Added AD7765 Antialias Protection Section ............................. 16

Added Driving the Modulator Inputs Directly Section ............ 19

Changes to Synchronization Section, Added Figure 35 ............ 21

Changes to Power Modes Section, Added

RESET

6/07—Revision 0: Initial Version

PWRDWN

Mode Section, Added Figure 38 ................................................... 22

Changes to Daisy Chaining Section ............................................. 23

Changes to Using the AD7765 Section ........................................ 27