QST108KT6 STMicroelectronics, QST108KT6 Datasheet - Page 10

• Manufacturer Part Number: QST108KT6
• Manufacturer: STMicroelectronics

Specifications of QST108KT6

• Lead Free Status / Rohs Status: Compliant

QST touch sensing technology
3.6
3.7
3.8
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Figure 3
samples are necessary to trigger the key detection or end of detection
Figure 3.
Self-calibration
On power-up, all keys are self-calibrated to provide reliable operation under almost any
conditions. The calibration phase is used to compute a reference value per key which is then
used by the process determining if a key is touched or not. The reference is an average of 8
single acquisitions. As a result, the calibration time of the system can be simply calculated
using the following formula: t
burst period is described in application note AN2547. For a maximum calibration duration
(t
Fast positive recalibration
The device autorecalibrates a key when its signal reflects a decrease in capacitance higher
than a fixed threshold (PosRecalTh) for a defined number of acquisitions (PosRecalI).
Forced key recalibration
A recalibration of the device may be issued at any time by sending to the QST device the
appropriate I
It is possible to recalibrate independently any individual key using an I
CAL
), please refer to
= Sampling point
shows an example of detection with DI=2 and EDI=2 meaning 3 consecutive
2
Detection signals
Hysteresis
C command or by tying the RESET pin to ground.
Section 6.6: Capacitive sensing characteristics on page
CAL
= 8 * Burst_Period. The methodology used to measure the
Time
2
C command.
Reference + EofDeTh
Key Detection signal
Reference + DeTh
Reference count
35.
QST108