Programmable Controller for Capacitance Touch Sensors AD7142 FEATURES FUNCTIONAL BLOCK DIAGRAM V V REF REF+ TEST Programmable capacitance-to-digital converter 29 28 27 36 ms update rate ( maximum sequence length) CIN0 30 POWER-ON RESET Better than 1 fF resolution 31 CIN1 LOGIC 32 CIN2 14 capacitance sensor input channels 1 CIN3 13 AV CC No external RC tuning components required 2 CIN4 CIN5 3 14 AGND Automatic conversion sequencer CIN6 4 16-BIT CALIBRATION - ENGINE On-chip automatic calibration logic CIN7 5 CDC CIN8 6 Automatic compensation for environmental changes 17 CIN9 7 DV CC Automatic adaptive threshold and sensitivity levels CIN10 8 18 CALIBRATION DGND1 CIN11 9 RAM On-chip RAM to store calibration data 10 CIN12 19 DGND2 11 CONTROL SPI-compatible serial interface (AD7142) CIN13 AND DATA 2 I C-compatible serial interface (AD7142-1) REGISTERS Separate V level for serial interface DRIVE C 12 Interrupt output and GPIO SHIELD 250kHz 15 EXCITATION 32-lead, 5 mm x 5 mm LFCSP VQ SRC SOURCE 16 2.6 V to 3.6 V supply voltage SRC Low operating current INTERRUPT SERIAL INTERFACE V AND GPIO Full power mode: less than 1 mA DRIVE 20 26 GPIO AND CONTROL LOGIC LOGIC Low power mode: 50 A 21 22 23 24 25 SDO/ SDI/ CS/ SCLK INT APPLICATIONS SDA ADD0 ADD1 Figure 1. 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 AD7142 and AD7142-1 are integrated capacitance-to- The AD7142 and AD7142-1 have on-chip calibration logic to digital converters (CDCs) with on-chip environmental account for changes in the ambient environment. The calibration calibration for use in systems requiring a novel user input sequence is performed automatically and at continuous intervals, method. The AD7142 and AD7142-1 can interface to external when the sensors are not touched. This ensures that there are no capacitance sensors implementing functions such as capacitive false or nonregistering touches on the external sensors due to a buttons, scroll bars, or wheels. changing environment. The CDC has 14 inputs channeled through a switch matrix to a The AD7142 has an SPI-compatible serial interface, and the 16-bit, 250 kHz sigma-delta (-) capacitance-to-digital 2 AD7142-1 has an I C-compatible serial interface. Both parts converter. The CDC is capable of sensing changes in the have an interrupt output, as well as a general-purpose input/ capacitance of the external sensors and uses this information to output (GPIO). register a sensor activation. The external sensors can be The AD7142 and AD7142-1 are available in a 32-lead, 5 mm arranged as a series of buttons, as a scroll bar or wheel, or as a 5 mm LFCSP VQ and operate from a 2.6 V to 3.6 V supply. The combination of sensor types. By programming the registers, the operating current consumption is less than 1 mA, falling to user has full control over the CDC setup. High resolution 50 A in low power mode (conversion interval of 400 ms). sensors require minor software to run on the host processor. Rev. A 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. SWITCH MATRIX 05702-001IMPORTANT LINKS for the AD7142* Last content update 06/27/2013 05:41 am (R) This product is not recommended for new designs. The AD7147 is recommended instead for new CapTouch designs. PARAMETRIC SELECTION TABLES DESIGN TOOLS, MODELS, DRIVERS & SOFTWARE Find Similar Products By Operating Parameters (R) AD714X Input CapTouch Programmable Controller Linux Driver DOCUMENTATION EVALUATION KITS & SYMBOLS & FOOTPRINTS AN-854: Sensor PCB Design Guidelines for the AD7142 and AD7143 Symbols and Footprints Capacitance-to-Digital Converters Applications (R) AN-929: Tuning the AD714x for CapTouch AN-857: Introduction to AD7142 Host Software Requirements AN-858: AD7142 Sensor Board In-Line Production Test Procedure DESIGN COLLABORATION COMMUNITY AN-830: Factors Affecting Sensor Response AN-829: Environmental Compensation on the AD7142: The Effects of Temperature and Humidity on Capacitance Sensors Collaborate Online with the ADI support team and other designers Webcast: Design And Develop Innovative And Robust Touch Sensor about select ADI products. Interfaces Using Capacitive-To-Digital Converters Capacitance Sensors for Human Interfaces to Electronic Equipment Follow us on Twitter: www.twitter.com/ADI News Like us on Facebook: www.facebook.com/AnalogDevicesInc MS-2210: Designing Power Supplies for High Speed ADC Capacitive Sensors Can Replace Mechanical Switches for Touch Control Programmable Medical Infusion Pumps Offer High Reliability and Performance DESIGN SUPPORT Building a reliable capacitive-sensor interface Submit your support request here: EE Times Names ACE Finalists Linear and Data Converters Embedded Processing and DSP Programmable 16-Bit CDC Targets Handheld Touch Screen Apps Programmable Capacitance-to-Digital Converter Includes 14 Telephone our Customer Interaction Centers toll free: Channels Americas: 1-800-262-5643 Capacitance-To-Digital Converter Eases Touch-Based Switch Europe: 00800-266-822-82 China: 4006-100-006 Implementation India: 1800-419-0108 Capacitance-To-Digital Converter Simplifies Touchpad Design Russia: 8-800-555-45-90 ADIs Capacitance-To-Digital Converter Quality and Reliability analogZONE Reviews The AD7142 CDC Lead(Pb)-Free Data Capacitive Touch Sensors Gain Fans iPods Lesson: Please Touch Capacitive Touch Sensors Fulfill Early Promise SAMPLE & BUY Motion Sensing Devices Make Integrated Systems Easy AD7142 Visit the AD7142 Product Page for more documentation. 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