AD5421

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

 

AC Performance Characteristics ................................................ 7

 

Timing Characteristics ................................................................ 7

 

Absolute Maximum Ratings............................................................ 9

 

Thermal Resistance ...................................................................... 9

 

ESD Caution.................................................................................. 9

 

Pin Configuration and Function Descriptions........................... 10

 

Typical Performance Characteristics ........................................... 12

 

Terminology .................................................................................... 18

 

Theory of Operation ...................................................................... 19

 

Fault Alerts .................................................................................. 19

 

External Current Setting Resistor ............................................ 20

 

Loop Current Range Selection.................................................. 20

 

Connection to Loop Power Supply .......................................... 20

 

On-Chip ADC ............................................................................ 21

 

Voltage Regulator ....................................................................... 21

 

Loop Current Slew Rate Control.............................................. 21

 

Power-On Default ...................................................................... 21

 

HART Communications ........................................................... 22

 

Serial Interface ................................................................................ 24

 

Input Shift Register .................................................................... 24

 

Register Readback ...................................................................... 24

 

DAC Register .............................................................................. 25

 

Control Register ......................................................................... 26

 

Fault Register .............................................................................. 27

 

Offset Adjust Register ................................................................ 28

 

Gain Adjust Register .................................................................. 28

 

Applications Information .............................................................. 30

 

Determining the Expected Total Error ................................... 30

 

Thermal and Supply Considerations ....................................... 31

 

Outline Dimensions ....................................................................... 32

 

Ordering Guide .......................................................................... 32

 

REVISION HISTORY

2/11—Revision 0: Initial Version