at42qt1481 ATMEL Corporation, at42qt1481 Datasheet - Page 19

• Manufacturer Part Number: at42qt1481
• Description: 48-key Qmatrix Ic
• Manufacturer: ATMEL Corporation

AT42QT1481
The QT1481 considers a hop to one of the other frequencies when the noise at the current
frequency consistently exceeds the threshold configured with NSTHR. To prevent true touch
events and other brief signal anomalies being considered as noise, the QT1481 employs
counters, termed noise integrators, to track the number of signal deltas that exceed the noise
threshold. It maintains two such counters, one for positive deltas and one for negative deltas.
The QT1481 considers a frequency hop only if both these counters reach the noise integrator
limit (NIL). The counters are reset to zero at the end of each matrix scan.
The QT1481 will not switch the frequency during calibration.
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9621B–AT42–06/11