TTP224 capacitive touch unreliable when using adapter

[lutkeveld]

I am using a TTP224 chip for capacitive touch sensing through 3mm wood.

If I run the chip via a LDO from battery, it works reliably.
When I plug in a charger, the circuit starts to produce false positives.

What would be the best way to combat this? Install an EMI (is this the problem?) filter between adapter and battery?
Or use some filter before the capacitive touch chip?

[janoc]

Change the adapter? Likely a cheapo switcher with a lot of ripple/noise upsetting the capacitive sensing. You can always put a common mode choke + some filtering capacitor or use higher voltage adapter with a local LDO to power the sensor, which will knock the ripple down as well.