AD7685

Data Sheet

TABLE OF CONTENTS

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

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

Typical Application Circuit ............................................................. 1

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

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

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

Timing Specifications....................................................................... 5

Absolute Maximum Ratings............................................................ 7

ESD Caution.................................................................................. 7

Pin Configuration and Function Descriptions............................. 8

Terminology ...................................................................................... 9

Typical Performance Characteristics ........................................... 10

Theory of Operation ...................................................................... 13

Circuit Information.................................................................... 13

Converter Operation.................................................................. 13

Typical Connection Diagram.................................................... 14

Analog Inputs.............................................................................. 15

Driver Amplifier Choice ........................................................... 16

Voltage Reference Input ............................................................ 16

Power Supply............................................................................... 16

Supplying the ADC from the Reference.................................. 17

Digital Interface.......................................................................... 17

CS Mode 3-Wire, No BUSY Indicator..................................... 18

CS Mode 3-Wire with BUSY Indicator ................................... 19

CS Mode 4-Wire, No BUSY Indicator..................................... 20

CS Mode 4-Wire with BUSY Indicator ................................... 21

Chain Mode, No BUSY Indicator ............................................ 22

Chain Mode with BUSY Indicator........................................... 23

Application Hints ........................................................................... 24

Layout .......................................................................................... 24

Evaluating the Performance of the AD7685............................... 24

True 16-Bit Isolated Application Example.............................. 25

Outline Dimensions....................................................................... 26

Ordering Guide .......................................................................... 27

REVISION HISTORY

7/14—Rev. C to Rev. D

Deleted QFN .................................................................. Throughout

Changed Application Diagram to Typical Application

Circuit ................................................................................................ 1

Change to Features Section ............................................................. 1

Added Patent Note, Note 1.............................................................. 1

Changes to Evaluating the Performance of the AD7685

Section.............................................................................................. 24

Updated Outline Dimensions....................................................... 26

Changes to Ordering Guide .......................................................... 27

8/11—Rev. B to Rev. C

Changes to Figure 6 and Table 7..................................................... 8

Updated Outline Dimensions....................................................... 26

Changes to Ordering Guide .......................................................... 27

3/07—Rev. A to Rev. B

Changes to Features and Table 1..................................................... 1

Changes to Table 3............................................................................ 4

Moved Figure 3 and Figure 4 to Page............................................. 6

Inserted Figure 6; Renumbered Sequentially................................ 8

Changes to Figure 13 and Figure 14............................................. 11

Changes to Figure 27...................................................................... 14

Changes to Table 9.......................................................................... 16

Changes to Figure 32...................................................................... 17

Changes to Figure 43...................................................................... 22

Changes to Figure 45...................................................................... 23

Updated Outline Dimensions....................................................... 26

Changes to Ordering Guide.......................................................... 27

12/04—Rev. 0 to Rev. A

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

Changes to Figure 17 Captions..................................................... 11

Changes to Power Supply Section ................................................ 17

Changes to Digital Interface Section ........................................... 18

Changes to CS Mode 4-Wire No Busy Indicator Section ......... 21

Changes to CS Mode 4-Wire with Busy Indicator Section....... 22

Changes to Chain Mode, No Busy Indicator Section................ 23

Changes to Chain Mode with Busy Indicator Section .............. 24

Added True 16-Bit Isolated Application Example Section ....... 26

Added Figure 47 ............................................................................. 26

Changes to Ordering Guide.......................................................... 28

4/04—Revision 0: Initial Revision

Rev. D | Page 2 of 28