QT111 QProx 8-pin Sensor

The QT111 is a touch sensor IC having recalibration timeouts (“max on-duration”) of 5 minutes and infinity.

This allows the device to be used in situations where recalibration timeouts are not desired, for example in

certain consumer, machine tool and process control applications where continuous touch over long periods is

desired, like hand-on-joystick sensors, dead-man switches, etc. Although the primary application of the device

is still as a ‘touch sensor’, longer timeouts also aknowledge alternate uses for the QT110 family, for example in

process controls.

The QT111 sensor is exactly the same in all respects to the QT110 with the following exceptions shown in bold

(refer to Table 2-1 in the QT110 datasheet):

Vdd

Gnd

Gnd

Gnd

Vdd

Vdd

All other operating modes, specifications, and wiring should be read from the QT110 data sheet.

Care should be taken in infinite timeout mode that the Cs and Cx capacitances and the Vcc supply

do not drift substantially over the course of a detection; if any of these parameters change

sufficiently during the course of an active detection (remember: drift compensation is never

performed during a detection event) the sensor can either ‘stick on’ after the detected object is

removed, or, the QT110’s apparent sensitivity will be substantially reduced for a period of time until

drift compensation can recover the proper reference level. If possible, uses the lowest gain setting

when using with long timeouts.

If the sensor ‘sticks on’ after the detected object or substance is removed from the sense element, the only way

to clear the sensor may be to remove power momentarily in order to induce a full recalibration.

DIP Package: DIP devices are marked 'QT111'

SO8 Package: Marked 'QT1' and also laserscribed '1'