AD7143

对于电容式触摸传感器的可编程控制器 Programmable Controller for Capacitance Touch Sensors

Product Details

The 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**

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Personal music and multimedia playersCell phones

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Digital still cameras

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Smart hand-held devices

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Television, A/V, and remote controls

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Gaming consoles

Data Sheet, Rev. 0, 1/07

### Features and Benefits

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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

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On-chip automatic calibration logic

Automatic compensation for environmental changes

Automatic adaptive threshold and sensitivity levels

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On-chip RAM to store calibration data

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I2C®-compatible serial interface

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Separate VDRIVE level for serial interface

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Interrupt output for host controller

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16-lead, 4 mm x 4 mm LFCSP-VQ

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2.6 V to 3.6 V supply voltage

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Low operating current

Full power mode: less than 1 mA

Low power mode: 50 µA