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

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

Automotive: Audio/Video Module

Cell Phone/Smart Phone: Touchscreen Controller

Digital Camera: Touchscreen Controller

HDTV: Control Buttons

Laser Printer: Touchscreen Controller

MP3 Player: Touchscreen Controller

Set Top Box: Touch Pads

White Goods: Control Buttons



Pricing and Availability

The 12-channel SX8633 (order code: SX8633I05AWLTRT), SX8634 (order code: SX8634I05AWLTRT) and SX8635 (order code: SX8635I05AWLTRT) are available in production quantities and are priced at $1.32, $1.38 and $1.43 respectively in 1,000-piece lots. The 1,000-piece price for the smaller pin-count, 8-channel SX8636 (order code: SX8636I05AULTRT), SX8638 (order code: SX8638I05AULTRT) and SX8639 (order code: SX8639I05AULTRT) are $1.24, $1.32 and $1.37 respectively. Semtech offers comprehensive design assistance, including field- and factory-based support. Data sheets, volume pricing, and delivery quotes, as well as evaluation kits and samples, are available by contacting http://www.semtech.com/info.