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AD7147 Dataheets PDF



Part Number AD7147
Manufacturers Analog Devices
Logo Analog Devices
Description CapTouch Programmable Controller
Datasheet AD7147 DatasheetAD7147 Datasheet (PDF)

CapTouch™ Programmable Controller for Single-Electrode Capacitance Sensors AD7147 FEATURES www.datasheet4u.com Programmable capacitance-to-digital converter (CDC) Femtofarad resolution 13 capacitance sensor inputs 9 ms update rate, all 13 sensor inputs No external RC components required Automatic conversion sequencer On-chip automatic calibration logic Automatic compensation for environmental changes Automatic adaptive threshold and sensitivity levels Register map is compatible with the AD7142 .

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CapTouch™ Programmable Controller for Single-Electrode Capacitance Sensors AD7147 FEATURES www.datasheet4u.com Programmable capacitance-to-digital converter (CDC) Femtofarad resolution 13 capacitance sensor inputs 9 ms update rate, all 13 sensor inputs No external RC components required Automatic conversion sequencer On-chip automatic calibration logic Automatic compensation for environmental changes Automatic adaptive threshold and sensitivity levels Register map is compatible with the AD7142 On-chip RAM to store calibration data SPI-compatible (serial-peripheral-interface-compatible) serial interface (AD7147) I2C-compatible serial interface (AD7147-1) Separate VDRIVE level for serial interface Interrupt output and general-purpose input/output (GPIO) 24-lead, 4 mm × 4 mm LFCSP 2.6 V to 3.3 V supply voltage Low operating current Full power mode: 1 mA Low power mode: 21.5 μA FUNCTIONAL BLOCK DIAGRAM ACSHIELD VCC 8 11 GND 10 BIAS 9 CIN0 19 CIN1 20 CIN2 21 CIN3 22 CIN4 23 EXCITATION SOURCE POWER-ON RESET LOGIC CIN6 1 CIN7 2 CIN8 3 CIN9 4 CIN10 5 CIN11 6 CIN12 7 SWITCH MATRIX CIN5 24 AD7147 CALIBRATION RAM 16-BIT Σ-Δ CDC CALIBRATION ENGINE CONTROL AND DATA REGISTERS VDRIVE 12 SERIAL INTERFACE AND CONTROL LOGIC INTERRUPT AND GPIO LOGIC 18 GPIO APPLICATIONS Cell phones Personal music and multimedia players Smart handheld devices Television, A/V, and remote controls Gaming consoles Digital still cameras SDO/ SDI/ SCLK CS/ SDA ADD0 ADD1 INT Figure 1. AD7147 Block Diagram The AD7147 is designed for single-electrode capacitance sensors (grounded sensors). There is an active shield output to minimize noise pickup in the sensor. The AD7147 has on-chip calibration logic to compensate for changes in the ambient environment. The calibration sequence is performed automatically and at continuous intervals as long as 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 AD7147 has an SPI-compatible serial interface, and the AD7147-1 has an I2C®-compatible serial interface. Both parts have an interrupt output, as well as a GPIO. There is a VDRIVE pin to set the voltage level for the serial interface independent of VCC. The AD7147 is available in a 24-lead, 4 mm × 4 mm LFCSP and operates from a 2.6 V to 3.6 V supply. The operating current consumption in low power mode is typically 26 μA for 13 sensors. GENERAL DESCRIPTION The AD7147 is designed for use with capacitance sensors implementing functions such as buttons, scroll bars, and wheels. The sensors need only one PCB layer, enabling ultra thin applications. The AD7147 is an integrated CDC with on-chip environmental calibration. The CDC has 13 inputs channeled through a switch matrix to a 16-bit, 250 kHz sigma-delta (∑-Δ) converter. The CDC is capable of sensing changes in the capacitance of the external sensors and uses this information to register a sensor activation. By programming the registers, the user has full control over the CDC setup. High resolution sensors require minor 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. Trademarks and registered trademarks are the property of their respective owners. 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. 06663-001 13 14 15 16 17 AD7147 TABLE OF CONTENTS Features .............................................................................................. 1 Applications....................................................................................... 1 www.datasheet4u.com Capacitance Sensor Behavior Without Calibration............... 23 Capacitance Sensor Behavior with Calibration...................... 24 Slow FIFO.................................................................................... 24 SLOW_FILTER_UPDATE_LVL .............................................. 24 Adaptive Threshold and Sensitivity ............................................. 25 Interrupt Output............................................................................. 27 CDC Conversion-Complete Interrupt .................................... 27 Sensor-Touch Interrupt ............................................................. 27 GPIO INT Output Control ....................................................... 29 Outputs ............................................................................................ 31 ACSHIELD Output .......................................................................... 3.


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