Data Sheet

3. Operation Specifics
3.1 Run Modes
3.1.1 Introduction
The QT1011 has three running modes which depend on the state of the SYNC pin (high or low).
3.1.2 Fast Mode
The QT1011 runs in Fast mode if the SYNC pin is permanently high. In this mode the QT1011 runs at
maximum speed at the expense of increased current consumption. Fast mode is useful when speed of
response is the prime design requirement. The delay between bursts in Fast mode is approximately 1 ms,
as shown in the following figure.
Figure 3-1. Fast Mode Bursts (SYNC Held High)
SNSK
SYNC
~1 ms
3.1.3 Low Power Mode
The QT1011 runs in Low Power (LP) mode if the SYNC pin is held low. 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). It then returns to LP mode after the key touch is
resolved, as shown in the following figure.
Figure 3-2. Low Power Mode (SYNC Held Low)
sleep sleep
SYNC
SNSK
sleep
fast detect
integrator
OUT
Key
touch
8 0 ms
3.1.4 SYNC Mode
It is possible to synchronize the device to an external clock source by placing an appropriate waveform
on the SYNC pin. SYNC mode can synchronize multiple QT1011 devices to each other to prevent cross-
AT42QT1011
© 2017 Microchip Technology Inc.
Datasheet
DS40001947A-page 10