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Capacitive touch chip manages power efficiently

Posted: 03 Sep 2007 ?? ?Print Version ?Bookmark and Share

Keywords:capacitive touch sensors? power management? MCU?


Quantum Research Group has released the newest member of its family of capacitive touch sensor products. The QT102, available in a SOT-23-6 package, is a one-channel touch on/touch off sensor chip with integral power management and safety functionality. These functions make it suitable for battery-driven applications and mains-driven products with stringent power management requirements, such as kitchen and home appliances, said Quantum Research Group.

The QT102 combines a toggle mode on/off switch with a hardware-programmable, auto switch-off function with override and reset capability. It also offers immediate shut-off in case of a system malfunction. The auto switch-off function is an important safety requirement. For example, in kitchen appliances it prevents overheating of the system if the user forgets to turn off the appliance after use.

"Power control and management features are key requirements for almost all applications," says Hal Philipp, CEO and founder, Quantum Research Group. "Combining new technologies such as capacitive touch sense control with timing functions for power management and safety will bring a new level of competitiveness to our customers."

The QT102 also has an internal power management control, running the part mostly in low-power mode and only switching temporarily to its high power, fast mode once a touch is detected. This guarantees a typical current consumption of 37?A at 3V supply voltage, while maintaining a very fast response time to touch. Additional features are automatic recalibration to ensure reliable operation in changing environments and a detect integrator which suppresses detection generated by electrical noise or unintentional contact with an object. A user-configurable output pin allows for easy interfacing back to a host MCU or to drive power loads via a MOSFET or bipolar transistor.

Target applications of the QT102 include touch control and auto-off of lighting controls, small domestic appliances such as irons, coffee makers and kettles, rice cookers, fans, flashlights, cordless headsets, children's toys, and even PC peripherals. Special versions of this part are possible since the device is largely firmware based and can be readily modified for sufficient OEM quantities.

The QT102 is sampling now. A demo board will be available early next month. The QT102 is priced under 50 cents in high volume quantities.

- Henri Arnold
EE Times Europe

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