Microchip Technology QTouch™ Sensor ICs

Microchip Technology QTouch™ Sensor ICs arms designers with robust, reliable capacitive touch controls used in economical and elegant touchscreens that respond to a wide variety of touch types and gestures. The Microchip QTouch IC family derives its robust and reliable characteristics from the signal processing in the decision logic, which eliminates false triggering due to electrostatic spikes or momentary unintentional touch or proximity. The sensors in the Microchip QTouch IC can drive single or multiple keys, and each key can be set for an individual sensitivity level. QTouch technology can be deployed in normal touch mode or high-sensitivity proximity mode. In proximity mode, highly sensitive charge transfer proximity sensing is used to detect an end-user's approaching finger and has the user interface interrupt the electronic equipment or electrical appliance to initiate a system function.

QTouch Technology Overview

Microchip Technology QTouch™ Sensor ICs

The QTouch devices are charging a sense electrode of unknown capacitance to a known potential. The electrode is typically a copper area on a printed circuit board. The resulting charge is transferred into a measurement circuit. By measuring the charge after one or more charge-and-transfer cycles, the capacitance of the sense plate can be determined. Placing a finger on the touch surface introduces external capacitance that affects the flow of charge at that point. This registers as a touch. QTouch microcontrollers can also be set up to detect the proximity of a finger, rather than absolute touch. Signal processing in the decision logic makes QTouch robust and reliable. False triggering due to electrostatic spikes or momentary unintentional touch or proximity is eliminated. QTouch sensors can drive single or multiple keys. Where multiple keys are used, each key can be set for an individual sensitivity level. Keys of different sizes and shapes can be used to meet both functional and aesthetic requirements. QTouch technology can be deployed in two ways, normal or 'touch' mode and high-sensitivity or 'proximity' mode. The highly sensitive charge transfer proximity sensing is used to detect an end-user's approaching finger, and have the user interface interrupt the electronic equipment or electrical appliance to initiate a system function. For excellent electromagnetic compatibility, QTouch sensors use spread-spectrum modulation and sparse, randomized charging pulses with long delays between bursts. Individual pulses can be as short as 5% or less of the intra-burst pulse spacing. The benefits of this approach include lower cross-sensor interference, reduced RF emissions and susceptibility, and low power consumption.

QTouch Library Features

  • Implements low-power, high-sensitivity, environmentally robust capacitive touch buttons, sliders, and wheels
  • Supports mutual capacitance and self-capacitance sensing
  • Up to 32 buttons in self-capacitance mode
  • Up to 256 buttons in mutual capacitance mode
  • Supports lumped mode configuration
  • One pin per electrode - no external components
  • Load compensating charge sensing
  • Parasitic capacitance compensation for mutual capacitance mode
  • Adjustable gain for superior sensitivity
  • Zero drift over the temperature and VDD range
  • No need for temperature or VDD compensation
  • Hardware noise filtering and noise signal de-synchronization for high conducted immunity
  • QTouch Library firmware and QTouch Composer tool

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เผยแพร่แล้ว: 2552-05-04 | อัปเดตแล้ว: 2565-03-11