Home > Products > Capacitance-to-digital controller provides accurate measurement and improved responsiveness for user interface controls

Mixed Signal/Analog

Capacitance-to-digital controller provides accurate measurement and improved responsiveness for user interface controls

12th June 2007

Analog Devices

ES Admin

0 0

Analog Devices’ new capacitance-to-digital converter (CDC) is a highly integrated touch controller that allows designers to quickly and easily add responsive user controls, such as scroll wheels and touch pads, to portable electronic devices. As the newest addition to Analog Devices’ family of CapTouch controllers for consumer applications, the AD7147 provides highly accurate measurement and responsiveness, and features the addition of an active shield feature for improved noise performance. Requiring only a single PCB for full implementation, the new CDC is ideal for ultra-thin mobile electronic devices.

The configurable AD7147 CDC features 13 capacitance inputs and femto farad resolution, allowing mobile electronics designers to implement a touch pad, scroll wheel, slider, or up to 36 buttons per device. The addition of integrated active shield technology protects the AD7147 from capacitance-to-ground pickup and other noise sources in the system, allowing designers the freedom to place the sensor away from the main system IC.

The analog front-end of the AD7147 has been improved, yielding a threefold improvement in sensor response compared to previous AD714x products. The improved response allows end-users to experience more accurate finger navigation and improved device performance, while continuing to offer designers per-channel sensitivity adjustment for sensor-response fine tuning. The AD7147 includes on-chip sensitivity algorithms that compensate for changes in temperature and humidity, and ensure that users with different finger sizes receive the same responsive sensor performance.

The AD7147 typically consumes 1 mA in full power mode, and just 50 μA in low-power mode, a 20% reduction compared to competitive products on the market. Additionally, the AD7147 has the industry’s lowest shutdown power consumption at only 2 μA.

The AD7147 includes an SPI (serial peripheral interface)-compatible serial interface, while the AD7147-1 features an I²C (inter-integrated circuit)-compatible serial interface. Both devices are sampling now and will be available in full production quantities in July 2007. Priced at $1.30 per unit in 1,000-unit quantities, both products are housed in 24-pin 4 mm × 4 mm LFCSPs.