EMI/EMC Compliance scheme

[gary36]

I am developing a system which is powered by 230V/AC. I am using a AC-DC converter (230VAC to 3.3V/2A-max) to power on board components. I have to make this product EMI/EMC compliant as per IEC61000 standard, essentially for surge and EFT. Now I have the following proposal for meeting the compliance

1. Choose the power supply already compliant for EMI/EMC (https://uk.tdk-lambda.com/KB/ZWS-B-Datasheet.pdf)
2. In addition to point No 1, add EMI filter and Surge suppressing devices before power supply as a line of defense

Please confirm if either of the above proposed method is Ok or should I adopt a different strategy?

 

[Easy peasy]

sounds like you are on the right path ...

 

[gary36]

Hi Easy peasy

Please confirm, which one to choose,Sl.No.1 or Sl.No2 as described in #1?

 

[Easy peasy]

No. 2 includes No.1 so both is implied in your post.

 

[gary36]

Hi Easy peasy

Sl.No2 requires additional investment, whereas Sl. No.1 is bit cheaper. So I am asking whether Sl.No.1 alone would suffice or should I really go for additional investment?

 

[Easy peasy]

impossible to tell - the golden rule of EMC compliance is: start with everything you can fit ....

 

[gary36]

Hi
Curious, but can EMI filter (as I proposed) withstand surge (2kV level) and EFT burst transients? The data sheet FN2030,https://www.schaffner.com/product-storage/datasheets/fn-2030/ does not detail about this

 

[Easy peasy]

perhaps you need to read the data sheet more closely - it clearly states 1100VDC P-N for 2 sec, and other ratings for P->E 2000Vac and 2550 VDC ... 2 sec

these are a bit light compared to a class Y2 cap - but I guess you get what you pay for...

 

[gary36]

Hi Easy peasy
Recently my customer told me that even though the power supply claims to be compliant to surge and EFT, still it is mandatory to provide basic protection for the DC line connected to load.

In that case, I am not sure where to begin, because I do not know what voltage level will be let through by the power supply and what current levels to assume. My load is FPGA and other bunch of ADC/DAC/op-amps etc. How to calculate the impedance of my circuit and estimate the peak current?

 

[Easy peasy]

easy - some 5W zeners on the DC lines ...

 

[gary36]

Hi Easy peasy

Some calculation tips would be helpful to choose the right TVS.

 

[Easy peasy]

reading data sheets and app notes for oneself can be very instructive ...

 

[gary36]

Looked at references. For protecting 5V DC line, I chose SMAJ6.0A. The clamp voltage suggests 10.5V at Ipp. But max rating for 5V devices are 5.25V. Suggest me the right solution

 

[Easy peasy]

see post #10