Hi all
I want to create positive and negative rails using two UCC12050DVE
Is this possible to treat them as any other isolated psu? whereby connecting one normally (GNDS to isolated GND.) and the other VISO to the GNDS of the other ? Making GNDS on one supply the negative output voltage?
Scott,
You have the basics down in that surface layers (air) have different spacing requirements compared to internal PCB layers. Some designers prefer not to introduce anything into the design that might compromise the isolation barrier and other customer like the use of PCB stitch caps and/or the addition of a physical HV leaded Y-capacitor across the isolation barrier. It really depends on how much EMI mitigation is needed based on what other HF signals might be present in the system, and how much isolation is required. Check out this E2E post here.
Also, I took a look at IEC 61010 and see that for parallel interior conductors on different layers (stitch cap), insulation thickness needs to be 0.4mm. The stitch cap construction is best described by "C" in the below diagram from IEC 61010.
Regards,
Steve
I must say, the responses to these question have been magnificent... Thank you
I can tell you now that your competitors do not answer like this 
I like the idea of a stitch cap using internal layers, ive just only ever used actual Y-Caps before.
I am targeting 600Vrms CATII reinforced insulation here... Does the above only apply to voltages <=300Vrms?
0.4mm internal insulation won't comprimise the 600Vrms reinforced isolation, right?
As my target voltage for isolation is 600Vrms CATII minimum, i am looking at IEC61010-2-033 (as this will be a handheld product)
Section K.101.4.3 states;
If we look at K.103
I can't find any reference to CATII in the 61010-2-033 tables, so perhaps i just need to confiorm with the pcb house that the insulator between the layers meets 9600V (which would actually give me CATIII rating) dielectric strength for my given layer-layer spacing?
