Semtech is in volume production of the first members of a 4D-Touch touchscreen controller family which senses in the X, Y, Z+ (proximity), and Z- (pressure) directions.
The family allows sensing in all four dimensions with proximity sensing so the user doesn’t have to initiate the user experience.
The product is aimed at smart phones, tablets, handheld GPS, automotive consoles, and POS terminals.
The devices integrate a proximity detection feature that gives OEMs the ability to introduce a sensing experience to their products before a user even touches the device.
This high resolution capacitive proximity sensing is implemented with Semtech’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.
Semtech’s 4D-Touc family includes both resistive and capacitive sensing platforms.
The first resistive touchscreen products support a proximity detection distance of 5 cm using any standard 4/5-wire analogue resistive panel.
They have a 12-bit A-D for coordinates and touch pressure measurement with current consumption of 30uA at 8kSPS rate.
The controllers not only calculate the X,Y coordinate of the touch, but also support capacitive proximity sensing (Z+) as well as pressure measurement (Z-) with tactile feedback via haptics.
Typical enhanced user experiences enabled by this type of technology includes waking up the system as the user moves within sensing range, adjusting the backlight brighter/dimmer as the user approaches the panel or even displaying hidden/key menus as the user’s hand gets close to the display.
Some products also have an integrated ability to drive LRA or ERM motors directly for haptic feedback emulating the mechanical tactile feedback users are accustomed to, as well as giving the appropriate strength of haptic feedback proportional to the pressure measurement.
Semtech has capacitive touch-button solutions so sensitive that a hand approaching within 10cm can automatically turn on the LEDs behind the control buttons and provide visual feedback to the user.
An LCD TV or monitor is an ideal application where these control buttons are typically hidden until someone reaches for them at which point they are turned on.
All Semtech’s 4D-Touch family are architected for low power applications in portable equipment dissipating as little as 0.4uA in standby mode.
ESD protection up to ±15kV ESD is integrated on-chip to reduce the customer’s BOM cost and board space from the requirement for external ESD protection typically used in touch applications.
They also come in miniature form factors as small as a 2mm x2mm WCSP.
