I am planning to build a simple and reliable power supply for a projetc with MCU (atmega88), tons of RGB leds (20mA), IR receiver, FETs and stuff.
The input is 220V/50Hz mains with EP (L,N, EP). Output is 5V, 1A at max.
The PS must work 24hours a day, 365days a year because MCU is always standby mode waiting for IR signal or mechnical switches to be switched.
I already have a torroid transformer 220V->12V 1.5A, so, i will use it.
After the rectifying bridge i will put LM2576 witch is a 52Khz 3A 5V buck converter. And voila, i have a pretty good PSU.
However, as i look at certified PSUs i see that they use X and Y filtering caps on mains side. I am sure there is good reason for it. Do i need to use it here to suppress EMI? If so, which parameters should i use for X and Y caps? Also, usually PSUs have metal case and the case is grounded. Should i also use metal case and ground it or i may safely leave it plastic and connect Y caps to the input PE wire?
How it all supposed to be done if one want to certify PSUs? I want this level of EMI suppression and safety.
Thanks you in advance.