AD7944

Data Sheet

Rev. C | Page 2 of 28

TABLE OF CONTENTS

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

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

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

Application Diagram........................................................................ 1

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

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

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

Absolute Maximum Ratings............................................................ 6

ESD Caution.................................................................................. 6

Pin Configuration and Function Descriptions............................. 7

Typical Performance Characteristics ............................................. 9

Terminology .................................................................................... 12

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

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

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

Conversion Modes of Operation.............................................. 13

Typical Application Diagram.................................................... 14

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

Driver Amplifier Choice ........................................................... 15

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

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

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

Data Reading Options ............................................................... 18

CS Mode, 3-Wire Without Busy Indicator ............................. 19

CS Mode, 3-Wire with Busy Indicator .................................... 20

CS Mode, 4-Wire Without Busy Indicator ............................. 21

CS Mode, 4-Wire with Busy Indicator .................................... 22

Chain Mode Without Busy Indicator ...................................... 23

Chain Mode with Busy Indicator............................................. 24

Applications Information .............................................................. 25

Layout .......................................................................................... 25

Evaluating AD7944 Performance............................................. 25

Outline Dimensions....................................................................... 27

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

REVISION HISTORY

2/16—Rev. B to Rev. C

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

Change to Transition Noise Parameter, Table 2 ........................... 3

Deleted Note 4, Table 2 .................................................................... 3

Changes to Figure 4.......................................................................... 7

Changed Typical Connection Diagram Section to Typical

Application Diagram Section........................................................ 14

Change to Typical Application Diagram Section....................... 14

Changes to Figure 23...................................................................... 14

Changes to Driver Amplifier Choice Section ............................. 15

Change to Reference Decoupling Section................................... 16

Changes to Reading During Conversion, Fast Host (Turbo

or Normal Mode) Section and Split Reading, Any Speed Host

(Turbo or Normal Mode) Section ................................................ 18

Changes to Figure 31...................................................................... 21

Changes to Evaluating AD7944 Performance Section .............. 25

Updated Outline Dimensions....................................................... 27

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

7/14—Rev. A to Rev. B

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

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

Changes to Figure 21...................................................................... 13

Changes to Data Reading Options Section................................. 18

8/10—Rev. 0 to Rev. A

Changes to Table 4, Conversion Time: CNV Rising Edge

to Data Available................................................................................5

10/09—Revision 0: Initial Version