24-key Qmatrix Touch Sensor 32-Pin TQFP

The AT42QT1245 device is a digital burst mode charge-transfer sensor, designed specifically for matrix layout touch controls. It includes all signal processing functions necessary to provide stable sensing under a wide variety of changing conditions. Only a few external parts are required for operation. The entire circuit can be built within a few square centimeters of single-sided PCB area. CEM-1 and FR1 punched, single-sided materials can be used for the lowest possible cost. The rear of the PCB can be mounted flush on the back of a glass or plastic panel using a conventional adhesive, such as 3M VHB two-sided adhesive acrylic film. The QT1245 employs transverse charge-transfer (QT) sensing, a technology that senses changes in electrical charge forced across two electrode elements by a pulse edge.

• Number of keys:
  • Up to 24
• Technology:
  • Patented charge-transfer (transverse mode), with frequency hopping
• Key outline sizes:
  • 6 mm × 6 mm or larger (panel thickness dependent); different sizes and shapes possible
• Key spacings:
  • 8 mm or wider, center to center (panel thickness dependent)
• Electrode design:
  • Two-part electrode shapes (drive-receive); wide variety of possible layouts
• Layers required:
  • One layer (with jumpers), two layers (no jumpers)
• Electrode materials:
  • PCB, FPCB, silver or carbon on film, ITO on film
• Panel materials:
  • Plastic, glass, composites, painted surfaces (low particle density metallic paints possible)
• Panel thickness:
  • Up to 50 mm glass, 20 mm plastic (key size dependent)
• Key sensitivity:
  • Individually settable via simple commands over communication interface
• Interface:
  • SPI
• Signal processing:
  • Self-calibration, auto drift compensation, noise filtering, Adjacent Key Suppression technology
• FMEA compliant design features
• IEC/EN/UL60730 compliant design features
  • UL approval
  • VDE compliance
  • For use in both class B and class C safety-critical products
• Detects and Reports Key Failure
• Power:
  • +3 V to 5 V
• Package:
  • 32-pin 7 × 7 mm TQFP RoHS compliant
  • 32-pin 5 × 5 mm QFN RoHS compliant