I am using 5V 1A SMPS power supply for power atmel MCU. I made a capacitive touch sensor with MCU but when i power my board on SMPS it is not working regularly. but than i power it on my computer USB Cable. it is working great.
Another interesting point is when i powered with SMPS board and then i touch ground or 5V plane it is working great. What kind of filter or circuit do i need to fix this problem.
Any suggestions ?
Different touch sensor designs are more or less sensitive to 50 Hz hum and high frequent noise. So you should describe your touch sensor setup thoroughly.
I guess, grounding the power supply output would help against both possible interference sources. If you plan an isolated power supply, an Y-capacitor would at least help against high frequent noise.