Flexible Touch-Sensor Chip Handles Up To 10 keys

Designed for consumer applications such as electrical and electronic appliances, gaming and mobile devices, the QT1101-QTouch charge-transfer IC is a self-contained digital controller capable of detecting near-proximity or touch on up to 10 individual keys. It allows electrodes to project independent sense fields through any dielectric such as glass or plastic and features a continuous self-calibration feature to eliminate the need for adjustment. Each channel operates independently of the others, and each can be tuned for a unique sensitivity level by changing a corresponding external capacitor, providing for highly flexible implementation. The IC employs a technique known as adjacent key suppression (AKS) to suppress touch from keys producing weaker signals and allows only the dominant key to activate. The company says that this solves the problem of finger overlap on tightly spaced keys. Spread spectrum burst technology provides a high degree of noise immunity. The device can also be synchronized with other QT chips or with an external source to suppress low-frequency interference. In its low-power mode, the chip consumes 60 µA at 3V. Few external components are required for a typical design. The sensor chip comes in a QFN-32 or 48SSOP, lead-free package and operates from a single supply of between 2.8V and 5.5V. The chip is available now priced at $1 each in high volume. For further information, contact Hal Philipp at QUANTUM RESEARCH GROUP LTD., Southampton, UK. 44 (0) 2380 565600.