Semtech describes the 4D-Touch touchscreen controller as ground-breaking. It can sense in the X, Y, Z+ (proximity), and Z- (pressure) directions in touch-interface applications such as smartphones, tablets, handheld GPS, automotive consoles, and PoS terminals. The high resolution capacitive proximity sensing is implemented with the company's proprietary analogue front-end design, which enables detection from a long distance as well as sensing through thick overlays and materials with low permittivity. Both resistive and capacitive sensing versions are available. The SX8654, -55, -56, -57 and -58 controllers support a proximity detection distance of more than 50mm using any standard four or five-wire analogue resistive panel. They have a 12bit ADC for co-ordinates and touch pressure measurement with current consumption as little as 30µA at 8k sample/s. The controllers calculate the X,Y co-ordinate of the touch, but also support capacitive proximity sensing (Z+) as well as pressure measurement (Z-) with tactile feedback via haptics. This added dimension can wake up the system as the user moves within sensing range, and to adjust the backlight brighter or dimmer as the user approaches the panel or even displaying hidden keys or menus as the user's hand gets close to the display. The devices are packaged in a 2x2mm WCSP.
