Datasheet

AD5421 Data Sheet
Rev. G | Page 2 of 36
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Companion Low Power Products .................................................. 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 3
Specifications ..................................................................................... 4
AC Performance Characteristics ................................................ 9
Timing Characteristics ................................................................ 9
Absolute Maximum Ratings .......................................................... 11
Thermal Resistance .................................................................... 11
ESD Caution ................................................................................ 11
Pin Configuration and Function Descriptions ........................... 12
Typical Performance Characteristics ........................................... 14
Terminology .................................................................................... 20
Theory of Operation ...................................................................... 21
Fault Alerts .................................................................................. 21
External Current Setting Resistor ............................................ 22
Loop Current Range Selection .................................................. 22
Connection to Loop Power Supply .......................................... 22
On-Chip ADC ............................................................................ 23
Voltage Regulator ....................................................................... 23
Loop Current Slew Rate Control .............................................. 23
Power-On Default ...................................................................... 24
HART Communications ........................................................... 24
Serial Interface ................................................................................ 26
Input Shift Register .................................................................... 26
Register Readback ...................................................................... 26
DAC Register .............................................................................. 27
Control Register ......................................................................... 28
Fault Register .............................................................................. 29
Offset Adjust Register ................................................................ 30
Gain Adjust Register .................................................................. 30
Applications Information .............................................................. 32
Determining the Expected Total Error ................................... 32
Thermal and Supply Considerations ....................................... 34
Outline Dimensions ....................................................................... 35
Ordering Guide .......................................................................... 36