Semtech Adds World’s Most Sensitive Proximity Function to Leading Capacitive Touchbutton Platform

The new SX863x capacitive touch button controllers come in 8- and 12-channel versions and feature a long range of proximity detection of 10cm (view SX863x proximity detection range video clip), allowing the sensor to control power-management and other convenience features such as system wake-up, LED wake-up and automatic backlight activation upon user detection. These devices support a wide range of button, slider and touch-wheel capacitive sensor panels that are increasingly being designed into white goods, mobile phones, media players, notebooks/netbooks, set top boxes and other consumer and industrial electronic products.

The SX863x devices simplify capacitive touch control design by providing a plug-and-play solution to reduce time-to-market while still allowing users to customize various parameters (for example: scan time, slave address, channel gain, sensitivity thresholds) for their specific applications, without the need for new firmware development. They also reduce the overall footprint and BOM (bill of materials) cost by incorporating dedicated capacitive sense inputs, without the need for external resistors and capacitors.

The capacitive analog interface on each of the six ICs in the SX863x platform is designed with a highly accurate ADC (analog-to-digital converter) that provides superior sensitivity to work with thick overlay materials (>5mm) for extremely robust ESD immunity and to support the 10cm range of proximity detection. Additionally, a smart automatic offset compensation function eliminates false triggers due to environmental factors such as temperature, humidity and dirt. With operating current consumption as low as 80µA, these ICs are an ideal choice for battery-powered applications.

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

“Unlike many competitive alternatives, the SX863x family integrates all the functional blocks necessary for touch sensing and proximity sensing in a tiny footprint that requires only one small capacitor. This simplifies the PCB design and reduces the overall solution BOM cost,” said Sam Massih, Director, Consumer Analog Products for Semtech. “The integrated, advanced features of the SX863x platform, coupled with ultra-low power consumption and extreme sensitivity, make these ICs ideal for a wide range of capacitive sensing applications.”

The devices in the SX863x platform include the 12-channel SX8633, SX8634 and SX8635, which are offered in 5mm x 5mm 32-pad QFN packages; and the 8-channel SX8636, SX8638 and SX8639 that come in 4mm x 4mm 28-pad QFN packages. Semtech guarantees all of these devices to operate over the extended (-40°C to +85°C) temperature range. All devices are Pb-free, halogen-free and fully RoHS compliant.

Key Features of the SX863x Platform
• Proximity capacitive touch sensor platform for button, slider and wheel control applications
• Proximity sensing up to 10cm
• Eight independent, 256-step LED drivers with auto-lightening mode and individual intensity and fading control
• High-resolution capacitive sensing (able to sense through overlay materials >5mm thick)
• Low power consumption optimized for battery-powered applications: 220µA (typ) in active mode; 80µA (typ) in doze mode; 8µA (typ) in sleep mode
• Auto offset compensation eliminates false triggers due to environmental factors
• Zero external components required for sensor input
• Multi-time in-field programmable firmware parameters for ultimate flexibility
Applications