QST104 datasheet(10/45 Pages) STMICROELECTRONICS

Part #	QST104

Description	Capacitive touch sensor device 4 keys with individual key state outputs or I2C interface

PDF	45 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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10 / 45 page

QST touch sensing technology

QST104

10/45

Caution:

When only one key is enabled or if keys are very close together, the common drift

compensation must be disabled or its rate must be reduced to ensure correct device

operation.

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.

The QST104 supports two AKS modes:

●

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 lowest key ID number 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.

Note:

All keys belonging to the same AKS group must have the same AKS mode.

QST104 Datasheet(PDF) 10 Page - STMicroelectronics