QST104 STMicroelectronics, QST104 Datasheet - Page 10

• Manufacturer Part Number: QST104
• Description: Capacitive touch sensor device 4 keys
• Manufacturer: STMicroelectronics

QST touch sensing technology
Caution:
3.11
Note:
10/45
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.
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:
●
●
In I
All keys belonging to the same AKS group must have the same AKS mode.
2
C mode, up to 8 AKS groups can be specified.
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.
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