BondBreaker Posted April 20, 2007 Report Share Posted April 20, 2007 I'm building a switching power supply and i've been studying commercial ones.I've noticed that underneath the photo coupler, there is usually a hole in the PCB.What is the purpose of this?Thanks Quote Link to comment Share on other sites More sharing options...
audioguru Posted April 20, 2007 Report Share Posted April 20, 2007 Maybe the hole separates the high voltage side from the low voltage side of the circuit, so that current leakage on the pcb (when it is damp from humidity?) doesn't matter. Quote Link to comment Share on other sites More sharing options...
indulis Posted April 21, 2007 Report Share Posted April 21, 2007 It's for "isolation" of primary to secondary. As isolation voltage levels change so do the creepage and clearances. The opto is often "weakest link" for creepage so you will often find a hole/slit under it. Quote Link to comment Share on other sites More sharing options...
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