at42qt1481 ATMEL Corporation, at42qt1481 Datasheet - Page 12

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

12
AT42QT1481
Figure 2-5.
Note:
One way to determine X line settling time is to monitor the fields using a patch of metal foil or a
small coin over the key (see
observed, as each of the keys along a particular X line are identical. The dwell time should
exceed the observed 95 percent settling of the X-pulse by 25 percent or more.
In almost all cases, Ry should be set equal to Rx, which ensures that the charge on the Y line is
fully captured into the Cs capacitor.
Figure 2-6.
The Dwell time is a minimum of ~125 ns – see
Drive Pulse Roll-off and Dwell Time
Probing X-Drive Waveforms With a Coin
Dwell time
Y gate
X drive
Figure
2-6). Only one key along a particular X line needs to be
Lost charge due to
inadequate settling
before end of dwell time
Section 5.13 on page 46
9621B–AT42–06/11