AD7142 Analog Devices, AD7142 Datasheet - Page 2

• Manufacturer Part Number: AD7142
• Description: Programmable Controller for Capacitance Touch Sensors
• Manufacturer: Analog Devices

Specifications of AD7142

• Resolution (bits): 16bit
• # Chan: 14
• Sample Rate: 250kSPS
• Interface: I²C/Ser 2-Wire,Ser,SPI
• Analog Input Type: Diff-Uni
• Ain Range: ± 2 pF (Delta C)
• Adc Architecture: Sigma-Delta
• Pkg Type: CSP

AD7142
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 3
Specifications..................................................................................... 4
Absolute Maximum Ratings............................................................ 8
Pin Configurations and Function Descriptions ........................... 9
Typical Performance Characteristics ........................................... 10
Theory of Operation ...................................................................... 12
Capacitance Sensor Input Configuration.................................... 14
Capacitance-to-Digital Converter................................................ 15
Noncontact Proximity Detection ................................................. 18
Environmental Calibration ........................................................... 22
SPI Timing Specifications (AD7142)......................................... 6
I
ESD Caution.................................................................................. 8
Capacitance Sensing Theory..................................................... 12
Operating Modes........................................................................ 13
CIN Input Multiplexer Setup .................................................... 14
Oversampling the CDC Output ............................................... 15
Capacitance Sensor Offset Control.......................................... 15
Conversion Sequencer ............................................................... 15
CDC Conversion Sequence Time ............................................ 16
CDC Conversion Results........................................................... 17
Recalibration ............................................................................... 18
Proximity Sensitivity .................................................................. 18
FF_SKIP_CNT............................................................................ 20
Capacitance Sensor Behavior Without Calibration............... 22
2
C Timing Specifications (AD7142-1) ..................................... 7
Rev. A | Page 2 of 72
Adaptive Threshold and Sensitivity ............................................. 24
Interrupt Output............................................................................. 26
Outputs ............................................................................................ 30
Serial Interface ................................................................................ 31
PCB Design Guidelines ................................................................. 36
Power-Up Sequence ....................................................................... 37
Typical Application Circuits ......................................................... 38
Register Map ................................................................................... 39
Detailed Register Descriptions ..................................................... 40
Outline Dimensions ....................................................................... 69
Capacitance Sensor Behavior with Calibration...................... 22
SLOW FIFO ................................................................................ 23
SLOW_FILTER_UPDATE_LVL .............................................. 23
CDC Conversion Complete Interrupt..................................... 26
Sensor Touch Interrupt.............................................................. 26
GPIO INT Output Control ....................................................... 28
Excitation Source........................................................................ 30
C
GPIO ............................................................................................ 30
Using the GPIO to turn on/off an LED................................... 30
SPI Interface ................................................................................ 31
I
V
Capacitive Sensor Board Mechanical Specifications ............. 36
Chip Scale Packages ................................................................... 36
Bank 1 Registers ......................................................................... 40
Bank 2 Registers ......................................................................... 50
Bank 3 Registers ......................................................................... 57
Ordering Guide .......................................................................... 69
2
C Compatible Interface........................................................... 33
SHIELD
DRIVE
Input ................................................................................. 35
Output ............................................................................. 30