AD7143 반도체 회로 부품 판매점
integrated capacitance-to-digital converter
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 Analog Devices |
www.DataSheet4U.com
FEATURES
Programmable capacitance-to-digital converter
25 ms update rate (@ maximum sequence length)
Better than 1 fF resolution
8 capacitance sensor input channels
No external RC tuning components required
Automatic conversion sequencer
On-chip automatic calibration logic
Automatic compensation for environmental changes
Automatic adaptive threshold and sensitivity levels
On-chip RAM to store calibration data
I2C®-compatible serial interface
Separate VDRIVE level for serial interface
Interrupt output for host controller
16-lead, 4 mm x 4 mm LFCSP-VQ
2.6 V to 3.6 V supply voltage
Low operating current
Full power mode: less than 1 mA
Low power mode: 50 μA
APPLICATIONS
Personal music and multimedia players
Cell phones
Digital still cameras
Smart hand-held devices
Television, A/V, and remote controls
Gaming consoles
GENERAL DESCRIPTION
The AD7143 is an integrated capacitance-to-digital converter
(CDC) with on-chip environmental calibration for use in
systems requiring a novel user input method. The AD7143
interfaces to external capacitance sensors implementing
functions, such as capacitive buttons, scroll bars, and
scroll wheels.
The CDC has eight inputs channeled through a switch matrix to
a 16-bit, 250 kHz sigma-delta (∑-Δ) capacitance-to-digital
converter. The CDC is capable of sensing changes in the
capacitance of the external sensors and uses this information to
register a sensor activation. The external sensors can be
arranged as a series of buttons, as a scroll bar or wheel, or as a
combination of sensor types. By programming the registers, the
user has full control over the CDC setup. High resolution
sensors require software to run on the host processor.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
Programmable Controller for
Capacitance Touch Sensors
AD7143
FUNCTIONAL BLOCK DIAGRAM
CIN0 15
CIN1 16
CIN2 1
CIN3 2
CIN4 3
CIN5 4
CIN6 5
CIN7 6
AD7143
POWER-ON
RESET
LOGIC
16-BIT
Σ-Δ
CDC
CALIBRA-
TION
ENGINE
CONTROL
AND
DATA
REGISTERS
CALIBRA-
TION
RAM
9 VCC
10 GND
CSHIELD 7
SRC 8
250kHz
EXCITATION
SOURCE
I2C SERIAL INTERFACE
AND CONTROL LOGIC
INTERRUPT
LOGIC
11 12 13
VDRIVE SDA SCLK
14
INT
Figure 1.
The AD7143 has on-chip calibration logic to account for
changes in the ambient environment. The calibration sequence is
performed automatically and at continuous intervals, while the
sensors are not touched. This ensures that there are no false or
nonregistering touches on the external sensors due to a
changing environment.
The AD7143 has an I2C-compatible serial interface and a
separate VDRIVE pin for I2C serial interface operating voltages
between 1.65 V and 3.6 V.
The AD7143 is available in a 16-lead, 4 mm × 4 mm LFCSP-VQ
and operates from a 2.6 V to 3.6 V supply. The operating
current consumption is less than 1 mA, falling to 50 μA in low
power mode (conversion interval of 400 ms).
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.
www.DataSheet4U.com
AD7143
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
I2C Timing Specifications............................................................ 5
Absolute Maximum Ratings............................................................ 6
ESD Caution.................................................................................. 6
Pin Configurations and Function Descriptions ........................... 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 11
Capacitance Sensing Theory..................................................... 11
Operating Modes........................................................................ 12
Capacitance Sensor Input Configuration.................................... 13
CIN Input Multiplexer Setup .................................................... 13
Capacitiance-to-Digital Converter............................................... 14
Oversampling the CDC Output ............................................... 14
Capacitance Sensor Offset Control.......................................... 14
Conversion Sequencer ............................................................... 14
CDC Conversion Sequence Time ............................................ 15
CDC Conversion Results........................................................... 16
Noncontact Proximity Detection ................................................. 17
Recalibration ............................................................................... 17
Proximity Sensitivity.................................................................. 17
Slow FIFO.................................................................................... 19
SLOW_FILTER_UPDATE_LVL .............................................. 19
Environmental Calibration ........................................................... 22
Capacitance Sensor Behavior without Calibration................ 22
Capacitance Sensor Behavior with Calibration...................... 23
Adaptive Threshold and Sensitivity ............................................. 25
Interrupt Output............................................................................. 26
CDC Conversion Complete Interrupt..................................... 26
Sensor Touch Interrupt.............................................................. 26
Serial Interface ................................................................................ 28
I2C Compatible Interface........................................................... 28
PCB Design Guidelines ................................................................. 31
Capacitive Sensor Board Mechanical Specifications ............. 31
Chip Scale Packages ................................................................... 31
Power-Up Sequence ....................................................................... 32
Typical Application Circuits ......................................................... 33
Register Map ................................................................................... 34
Detailed Register Descriptions ..................................................... 35
Bank 1 Registers ......................................................................... 35
Bank 2 Registers ......................................................................... 43
Bank 3 Registers ......................................................................... 47
Outline Dimensions ....................................................................... 55
Ordering Guide .......................................................................... 55
REVISION HISTORY
1/07—Revision 0: Initial Version
Rev. 0 | Page 2 of 56
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