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Overview
Features and Benefits
- 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
- See datasheet for additional features
Product Details
The AD7147 CapTouch™ controller is designed for use with capacitance sensors implementing functions such as buttons, scroll bars, and wheels. The sensors need only one PCB layer, enabling ultrathin 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 (Σ-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.
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 con-sumption in low power mode is typically 26 μA for 13 sensors.
Applications
- Cell phones
- Personal music and multimedia players
- Smart handheld devices
- Television, A/V, and remote controls
- Gaming consoles
- Digital still cameras
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Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
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Analog Dialogue
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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.
