AD7156
Rev. 0 | Page 2 of 28
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block 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 ............................................. 8
Theory of Operation ...................................................................... 11
Capacitance-to-Digital Converter ............................................ 11
CAPDAC ..................................................................................... 11
Comparator and Threshold Modes .......................................... 12
Adaptive Threshold .................................................................... 12
Sensitivity..................................................................................... 12
Data Average ............................................................................... 13
Hysteresis ..................................................................................... 13
Timeout ........................................................................................ 13
Auto-DAC Adjustment .............................................................. 14
Power-Down Timer ................................................................... 14
Register Descriptions ..................................................................... 15
Status Register ............................................................................. 16
Data Registers ............................................................................. 17
Average Registers ........................................................................ 18
Fixed Threshold Registers ......................................................... 18
Sensitivity Registers ................................................................... 18
Timeout Registers ....................................................................... 18
Setup Registers ............................................................................ 19
Configuration Register .............................................................. 20
Power-Down Timer Register .................................................... 21
CAPDAC Registers .................................................................... 21
Serial Number Register .............................................................. 21
Chip ID Register ......................................................................... 21
Serial Interface ................................................................................ 22
Read Operation........................................................................... 22
Write Operation.......................................................................... 22
AD7156 Reset ............................................................................. 23
General Call ................................................................................ 23
Hardware Design Considerations ................................................ 24
Overview ..................................................................................... 24
Parasitic Capacitance to Ground .............................................. 24
Parasitic Resistance to Ground ................................................. 24
Parasitic Parallel Resistance ...................................................... 24
Parasitic Serial Resistance ......................................................... 25
Input Overvoltage Protection ................................................... 25
Input EMC Protection ............................................................... 25
Power Supply Decoupling and Filtering .................................. 25
Application Examples ................................................................ 26
Outline Dimensions ....................................................................... 27
Ordering Guide .......................................................................... 27
REVISION HISTORY
10/08—Revision 0: Initial Version
