at42qt2100 ATMEL Corporation, at42qt2100 Datasheet - Page 14

• Manufacturer Part Number: at42qt2100
• Description: Qtouch Touch Sensor Ic
• Manufacturer: ATMEL Corporation

4.3
4.3.1
4.3.2
14
Signal Processing
AT42QT2100
Power-up Self-calibration
Drift Compensation
Figure 4-1.
On power-up, or after reset, all 10 channels are typically calibrated and operational within
350 ms.
This operates to correct the reference level of each key automatically over time; it suppresses
false detections caused by changes in temperature, humidity, dirt and other environmental
effects.
The QT2100 drifts “towards touch” at a rate limited to 1 count every 3 seconds, and “away
from touch” at a rate limited to 1 count every 0.5 seconds. Reference drift is paused during
touch detection, and for 2 seconds after touch detection ends. These timings may be slower in
“Sync” mode, or where asynchronous acquisition is triggered with LPB, as timing calculations
are derived from the acquisition interval.
DRDY
Burst 1
Burst 2
Burst 3
DRDY
Burst 1
Burst 2
Burst 3
SCK
DRDY Cycle
Burst 1
Burst 1
Burst 1
Burst 2
Burst 2
Burst 2
Without Communications
With Communications
Burst 3
Burst 3
Burst 3
Processing
Processing
Processing
& Sleep
& Sleep
& Sleep
Burst 1
Burst 1
Burst 1
Burst 2
Burst 2
Burst 2
9554CX–AT42–11/11
Burst 3
Burst 3
Burst 3