How to combine proximity detection with PresSense

AN3431

14/18

Doc ID 019017 Rev 1

3

How to combine proximity detection with

A proprietary technique exists which detects proximity events as a user approaches. The big

advantage of this technique is that backlighting can be illuminated as the user approaches

even before the actual touch event. This unique feature is implemented in PresSense

capacitive sensing technologies with limited external components.

For proximity event detection the conductive metal cover is connected to a capacitive

sensing channel of the touch sensing microcontroller device. The connection is shown in

Figure 7. After proximity detection has taken place the metal layer is grounded and a touch

can be detected. If no touch occurs after a given amount of time or if the detection of the

touch ends, the connection is switched back to the proximity detection.

Figure 7.

Proximity detection

b.

This technology is patent pending.