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AD7143:  Programmable Controller for Capacitance Touch Sensors

Product Details


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 (Σ-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.

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 I2 serial interface operating voltages between 1.65 V and 3.6 V.

The AD7143 is available in a 16-lead, 4 mm x 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).

Applications

  • Personal music and multimedia players
  • Cell phones
  • Digital still cameras
  • Smart hand-held devices
  • Television, A/V, and remote controls
  • Gaming consoles

Data Sheet, Rev. 0, 1/07

FEATURES and BENEFITS

  • 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

Functional Block Diagram for AD7143

OF NOTE ...

This product is not recommended for new designs. The AD7148 is recommended instead for new CapTouch® designs.

Documentation

Title Content Type File Type
AD7143: Programmable Controller for Capacitance Touch Sensors Data Sheet (Rev 0, 01/2007) (pdf, 996 kB) Data Sheets PDF
AN-854: Sensor PCB Design Guidelines for the AD7142 and AD7143 Capacitance-to-Digital Converters (Rev. A, 2/07)  (pdf, 582 kB) Application Notes PDF
AN-929: Tuning the AD714x for CapTouch® Applications  (pdf, 618 kB) Application Notes PDF
AN-857: Introduction to AD7142 Host Software Requirements  (pdf, 76 kB) Application Notes PDF
AN-856: AD7142 Applications Using Sensor Buttons  (pdf, 122 kB) Application Notes PDF
AN-858: AD7142 Sensor Board In-Line Production Test Procedure  (pdf, 124 kB) Application Notes PDF
AN-833: Using the AD7142 and a Capacitive Sensor to Develop a Single-Push Digital Shutter Button  (pdf, 99 kB) Application Notes PDF
AN-830: Factors Affecting Sensor Response  (pdf, 161 kB) Application Notes PDF
AN-829: Environmental Compensation on the AD7142: The Effects of Temperature and Humidity on Capacitance Sensors  (pdf, 101 kB) Application Notes PDF
Webcast: Design And Develop Innovative And Robust Touch Sensor Interfaces Using Capacitive-To-Digital Converters
This Webcast will focus on the design and development of CDC-based touch sensors and their application, cite CDC product examples such as the AD7142, and explore development tools provided by ADI.
Webcasts WEBCAST
Capacitance Sensors for Human Interfaces to Electronic Equipment
(Analog Dialogue, Vol. 40, October, 2006)
Analog Dialogue HTML
MS-2210: Designing Power Supplies for High Speed ADC  (pdf, 327 kB) Technical Articles PDF
Capacitance Sensors for Human Interfaces to Electronic Equipment
(Analog Dialogue, Vol. 40, October, 2006)
Technical Articles HTML
Motion Sensing Devices Make Integrated Systems Easy
(Electropages, 11/24/2006)
Product Reviews HTML
2008 Medical Solution Profile  (pdf, 126 kB)
High Performance ICs for Medical Imaging, Patient Monitoring, and Instrumentation
Overview PDF
Leading Inside Advertorials: Providing an Edge in Capacitive Sensor Applications  (pdf, 85 kB) Overview PDF
Leading Inside Advertorials: Boost Precision and Accuracy with Single Chip Capacitance- and Impedance-to-Digital Converters  (pdf, 482 kB) Overview PDF
Touch Controller System Block Diagram Overview HTML
What are Capacitive Sensors and how are they used? FAQs/RAQs HTML
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
AD714X Input CapTouch® Programmable Controller Linux Driver Device Drivers HTML

Evaluation Kits & Symbols & Footprints

Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.

SampleSample & Buy

Price, packaging, availability

Price Table Help

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


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