T
treez
Guest
Hi,
We needed to get a PCB (version 2) made up of our 60W Offline Flyback (PFC’d) LED driver. We needed it quickly so that our software engineer had something to work with.
I couldn’t fit all the components on the PCB, therefore, I stole room from the AC filter part of the board, to give to other parts of the circuit. Now , as expected, this PCB fails EMC.
Attached is the EMC filter schematic, and a picture of the EMC filter on the PCB, showing how tightly close together the AC filter components are. (AC filter part is outlined in light blue)
However, this is the only board that we now have for the purposes of optimising the EMC filter….in other words, we must repeatedly modify this board and repeatedly put it back through conducted EMC testing, until we get a pass. In the EMC test, I will have to de-solder some of the small 22nF X2 capacitors and replace them with bigger ones, (220nF) wired into their pads with twisted “flying wires”. Obviously this is less than ideal. How much extra problem with high frequency common mode emissions do you think that such a “flying wire” modified EMC filter will give us?
We needed to get a PCB (version 2) made up of our 60W Offline Flyback (PFC’d) LED driver. We needed it quickly so that our software engineer had something to work with.
I couldn’t fit all the components on the PCB, therefore, I stole room from the AC filter part of the board, to give to other parts of the circuit. Now , as expected, this PCB fails EMC.
Attached is the EMC filter schematic, and a picture of the EMC filter on the PCB, showing how tightly close together the AC filter components are. (AC filter part is outlined in light blue)
However, this is the only board that we now have for the purposes of optimising the EMC filter….in other words, we must repeatedly modify this board and repeatedly put it back through conducted EMC testing, until we get a pass. In the EMC test, I will have to de-solder some of the small 22nF X2 capacitors and replace them with bigger ones, (220nF) wired into their pads with twisted “flying wires”. Obviously this is less than ideal. How much extra problem with high frequency common mode emissions do you think that such a “flying wire” modified EMC filter will give us?