Hi, I would like to learn and know more about how to design CMC filter for an AC to DC LED driver (75W to 100W). If there is any step by step guide with necessary formulas, I would be very grateful.
Thanks in advance
In designing CMC filters, we usually iterate until we get to the needed inductance. You can start off with a small CMC and work your way up until you get a passing EMI scan. Usually for 75 to 100W designs, we start at around 10mH. Take note that this only filters common mode noise so you would need to optimize the other EMI filter components to get desired EMI filtering.
There are two ways of choosing a CMC: either you use an off-the-shelf CMC or you can create your own.
If you want to use an off-the-shelf CMC, here are some considerations:
If you want to create your own custom CMC:
I've attached a sample custom CMC specification. These are used by DER-801 for input and output CMCs.