Datasheet

3. Operation Specifics
3.1 Acquisition Modes
3.1.1 Introduction
The OUT pin of the QT1012 can be configured to be active high or active low.
• If active high then:
– “on” is high
– “off” is low
• If active low then:
– “on” is low
– “off” is high
3.1.2 OUT Pin
The QT1012 runs in Low Power (LP) mode. In this mode it sleeps for approximately 80 ms at the end of
each burst, saving power but slowing response. On detecting a possible key touch, it temporarily
switches to fast mode until either the key touch is confirmed or found to be spurious (via the detect
integration process).
• If the touch is confirmed, the OUT pin is toggled and the QT1012 returns to LP mode (see figure
"Low Power Mode: Touch Confirmed" below).
• If the touch is not valid then the chip returns to LP mode but the OUT pin remains unchanged (see
figure "Low Power Mode: Touch Denied" below).
Figure 3-1. Low Power Mode: Touch Confirmed (Output in Off Condition)
SNSK
sleep sleep
fast detect
integrator
OUT
Key
touch
~80 ms
Figure 3-2. Low Power Mode: Touch Denied (Output in Off Condition)
SNSK
Sleep
Fast detect
integrator
Key
touch
~80 ms
Sleep Sleep
OUT
Sleep
3.2 Detect Threshold
The device detects a touch when the signal has crossed a threshold level. The threshold level is fixed at
10 counts.
AT42QT1012
© 2017 Microchip Technology Inc.
Datasheet
DS40001948A-page 10