QT220-IG QUANTUM [Quantum Research Group], QT220-IG Datasheet - Page 7

• Manufacturer Part Number: QT220-IG
• Description: 2 KEY QTOUCH SENSOR IC
• Manufacturer: QUANTUM [Quantum Research Group]

3.6 CROSSTALK PRECAUTIONS
Adjacent sense traces might require intervening ground
traces in order to reduce capacitive cross bleed if high
sensitivity is required or high values of delta-Cx are
anticipated (for example, from direct human touch to an
electrode connection). In normal touch applications behind
plastic panels this is almost never a problem regardless of
how the electrodes are wired.
LQ
7
Higher values of Rsns will make crosstalk problems worse;
try to keep Rsns to 22K or less if possible.
In general try to keep the QT220 close to the electrodes and
reduce the adjacency of the sense wiring to ground planes
and other signal traces; this will reduce the Cx load, reduce
interference effects, and increase signal gain.
The one and only valid reason to run ground near SNS
traces is to provide crosstalk isolation between traces, and
then only on an as-needed basis.
QT220R R1.02/0905