at42qt1011 ATMEL Corporation, at42qt1011 Datasheet - Page 5

• Manufacturer Part Number: at42qt1011
• Description: One-channel Touch Sensor Ic
• Manufacturer: ATMEL Corporation

3.1.3
3.1.4
9542G–AT42–03/10
Low Power Mode
SYNC Mode
Figure 3-1.
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
Figure 3-2.
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-interference, or it can be used to enhance noise immunity from low
frequency sources such as 50Hz or 60Hz mains signals.
The SYNC pin is sampled at the end of each burst. If the device is in Fast mode and the SYNC
pin is sampled high, then the device continues to operate in Fast mode
SYNC is sampled low, then the device goes to sleep. From then on, it will operate in SYNC
mode
signal should be longer than the burst length
(Figure
SYNC
SNSK
OUT
3-2). Therefore, to guarantee entry into SYNC mode the low period of the SYNC
Fast Mode Bursts (SYNC Held High)
Low Power Mode (SYNC Held Low)
SNSK
SYNC
~80 ms
Sleep
~1ms
Figure 3-2 on page
Sleep
(Figure 3-3 on page
Fast detect
5.
integrator
6).
(Figure 3-1 on page
AT42QT1011
Sleep
5). If
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