QST108 datasheet(10/38 Pages) STMICROELECTRONICS

Part #	QST108

Description	Capacitive touch sensor device 8 keys with individual key state outputs or I2C interface

PDF	38 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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10 / 38 page

QST touch sensing technology

QST108

10/38

3.11

Adjacent key suppression (AKS™)

Adjacent key suppression (AKS™) is a Quantum-patented feature which prevents multiple

keys from responding to a single touch. This can happen with closely spaced keys, or a

scroll wheel that has buttons very near it.

AKS operates by comparing signal strengths from keys within a group of keys to suppress

touch detections from those that have a weaker signal change than the dominant one.

The QST108 supports two AKS algorithms:

●

Locking AKS

Once a key is considered as “touched”, all other keys are locked in an untouched state.

To unlock these keys, the touched key must return to an untouched state. Then, the key

having the highest signal level is declared as the “touched” one.

●

Unlocking AKS

On each acquisition, the signal strengths from each key are compared and the key with

the highest signal level is declared as the “touched” one.

In I2C mode, up to 8 AKS groups can be specified.

QST108 Datasheet(PDF) 10 Page - STMicroelectronics