AT42QT1012_10 Datasheet, PDF (21/28 Pages) ATMEL Corporation – One-channel Toggle-mode Touch Sensor IC with Power Management Functions

AT42QT1012
4.5 Power On
Electrode trace routing: Keep the electrode trace (and the electrode itself) away from other
signal, power, and ground traces including over or next to ground planes. Adjacent switching
signals can induce noise onto the sensing signal; any adjacent trace or ground plane next to, or
under, the electrode trace will cause an increase in Cx load and desensitize the device.
Bypass Capacitor: Important – For proper operation a 100 nF (0.1 µF) ceramic bypass
capacitor must be used directly between Vdd and Vss, to prevent latch-up if there are
substantial Vdd transients; for example, during an ESD event. The bypass capacitor should be
placed very close to the Vss and Vdd pins.
On initial power up, the QT1012 requires approximately 250 ms to power on to allow power
supplies to stabilize. During this time the OUT pin state is not valid and should be ignored.
Note that recalibration takes approximately 200 ms, so the QT1012 takes approximately 450 ms
in total from initial power on to become active.
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