Capacitive Touch Button Controllers

Semtech Corp.'s SX863xcapacitive touch button controllers come in 8 and 12-channel versions andfeature a long range of proximity detection of 10 cm (viewSX863x proximity detection range video clip), allowing the sensor tocontrol power-management and other features such as system wake-up, LED wake-upand automatic backlight activation upon user detection. These devices support awide range of button, slider and touch-wheel capacitive sensor panels that areincreasingly being designed into white goods, mobile phones, media players,notebooks/netbooks, set top boxes and other consumer and industrial electronicproducts.

The SX863xdevices simplify capacitive touch control design by providing a plug-and-playsolution to reduce time-to-market while still allowing users to customizevarious parameters (for example:scantime, slave address, channel gain, sensitivity thresholds) for their specificapplications, without the need for new firmware development. They also reducethe overall footprint and BOM cost by incorporating dedicated capacitive senseinputs, without the need for external resistors and capacitors.

The capacitive analoginterface on each of the six ICs in the SX863xplatform is designed with a highly accurate A dc (analog-to-digital converter)that provides superior sensitivity to work with thick overlay materials(>5 mm) for extremely robust ESD immunity and to support the 10 cm range ofproximity detection. Additionally, a smart automatic offset compensationfunction eliminates false triggers due to environmental factors such astemperature, humidity and dirt.

The SX863x platform integrates eight, 256-step LED driverswith individual intensity (linear or logarithmic) fading control optimized forhuman vision. This allows design of buttons that automatically fade in whentouched and fade out when released, with interval speed and initial and finallight intensity levels set by the designer.

The devices in the SX863x platform include the 12-channelSX8633, SX8634 and SX8635, which are offered in 5 x 5 mm 32-pad QFN packages;and the 8-channel SX8636, SX8638 and SX8639 that come in 4 x 4 mm 28-pad QFNpackages. Semtech guarantees all of these devices to operate over the extended(-40 to +85C) temperature range. All devices are Pb-free, halogen-free and fullyRoHS compliant.

Capacitive Touch Button Controllers