Touch Sensors Press For Low Costs, Streamlined Design

Some Examples
Building richer user interfaces, Atmel’s AT42QT family of charge-transfer, capacitive touchscreen controllers enables two-touch gestures for intuitive interfaces with the ability to track and report one or two simultaneous touches as separate X and Y positions. Gestures include tap, double tap, flick and drag, as well as two-touch actions, i.e., zoom in/out and rotate.

Initial family members, the AT42QT5320 and AT42QT5480, support screen sizes up to 8 in. with a 16:9 aspect ratio. The AT42QT5320 comes in a 5- by 5-mm quad flat no-lead (QFN) package while the AT42QT5480 is available in 5- by 5-mm ball-grid array (BGA), 7- by 7-mm QFN and a 10- by 10-mm thin quad flat pack (TQFP). The RoHS-compliant (Restrictions on Hazardous Substances) controllers will arrive in the first quarter of 2009.

To boost functionality in space-limited designs, Leadis offers the 5- by 5- by 0.8-mm LDS6040 PureTouch capacitive touch controller with integrated LED and VibeTonz-ready haptics drivers (see the figure). For touch-based input controls including sliders, scroll wheels, and buttons, the device provides 15 sensor inputs, configurable as LED drivers delivering up to 8 mA. It operates with a 1.8-V touch supply, and LED and haptics supply voltage ranges of 3 to 5 V. Typical power consumption is 150 µW in full-power mode.

Leadis’ TapTouch 15-channel capacitive touch controller supports up to 56 independent touch zones, lowering the cost of adding capacitive touch in high-button-count designs. The technology’s two-layer sensor array allows each sensor to support multiple touch zones, eliminating the need for multiple touch controllers. According to the company, it minimizes experience-inhibiting first-touch latency by enabling continuous scanning of touch zones without the high power consumption common to low- or no-latency implementations.