Touch-panel controller targets media-device interfaces

Atmel, in the form of its recently acquired subsidiary, Quantum Research Group, has introduced a touch controller that combines a slider control with buttons, an integrated LED controller, and GPIO (general-purpose-input/output) functions. The AT42QT2160, part of the company's new QTouch series, uses charge-transfer technology to control as many as 16 touch keys with a slider that you can configure to use two to eight of the touch-key channels. If you need an extra-long slider control, you can add interpolation between points with a resistive-touch-sensor element.

The chip can also control as many as 11 LEDs through a host-controlled PWM-output function, eliminating the need for an external LED controller.

Atmel designed the device for use as a multimedia-HMI (human-machine-interface) controller in mobile phones and consumer electronics, such as personal media players. It operates from 1.8 to 5.5V, and you can also use it in applications such as digital still cameras, PDAs (personal digital assistants), and handheld gaming devices. Like previous chips using the charge-transfer technology, the 2160 claims high immunity to EMI (electromagnetic interference) through spread-spectrum modulation and filtering algorithms, calibration of the device over its lifetime, and designer-defined sensitivity thresholds for individual keys. AKS (adjacent-key suppression) intelligently suppresses signals from nearby keys so that only the keys that a user intends to touch register a touch.

The AT42QT2160 has three GPIOs with PWM capability and eight shared-output ports that provide additional standard outputs for the host without adding cost or using an extra I/O-expansion device. You configure the device with an I²C (inter-integrated-circuit) interface. You might design touch-button-sensor electrodes of any arbitrary size greater than 6×6 mm and of arbitrary shape, as copper pads on the PCB (printed-circuit board) or a flexible circuit. The chip senses touches to those pads through glass or plastic as thick as 2.5 mm.

Samples of the AT42QT-2160 are available now in a 28-pin, 4×4-mm QFN package; it sells for 98 cents (10,000). An evaluation board, which comes with an I²C-to-USB converter to connect to a PC, costs $82.50.