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PCB Special Requirements needed when designing Power Electronics

@alberme96 , 04-24-2020, 09:34 AM
I am planning to do a power supply with a resonant flyback topology for the "Advanced Hardware Design" course, and I remember my profs. at University warned me about the PCB layout requirements for doing Power Electronics boards, they talked me about doing something they called “islands” so as to reduce the parasite impedance of the connection between the elements of the circuit. So my question is, does anybody know if there are special requirements or tips for doing power electronics PCB design and layout? And in case there are, does anybody know where can I find more information about this topic? My circuit would be a 65W output converter…

Thank you all in advanced!
robertferanec , 04-27-2020, 05:35 AM
I have only used "islands" once and it was like in year 2003. It was on my very first complex CPU board and I did it because it was recommended in some books. Since then - I have never used it - always solid grounds and I have had no problems.

I am not expert for power electronics, but some of the CPU boards I have designed take quite a lot of power (e.g. 150A to CPU Core) and still designed on one solid GND without any islands. However if you are doing special power circuits, maybe someone also could share their experience? There may be situations when you may want to use them - I would still consider to use islands if there were some sensitive circuits or higher voltage or something really noisy etc.
@alberme96 , 04-27-2020, 10:37 AM
Thank you so much for the response!
mir0mik , 05-06-2020, 03:45 PM
65W is not much, but if your design allows it, then use them (but correctly)... Solid grounds are good for high speed but in SMPS it's different, the power ground is a mess.

Robert - draining 150A to the core was more less DC and is different from SMPS. Also the 150A was probably delivered by multiple BUCK converters. In SMPS the power stage switches a lot of energy - usually all the energy at once (if not divided to parallel states) so there is a lot of noise.

EDIT: Look for the hot loops and hot spots for the resonant flyback and try to minimise them.
@alberme96 , 05-09-2020, 04:13 AM
Thank you mir0milk for your answer! So do you know any reference I can read about using these islands properly?
mir0mik , 05-09-2020, 04:08 PM
Hi @alberrme96, this is not so easy. The island are unique for each design. What you need to learn is:

- how the SMPS type you are going to do works
- how SMPS works
- what are ground loops
- what are hot loops and hot spots

Those are the basic, where you should start. Just google anything you can find about those topics.
@alberme96 , 05-09-2020, 04:16 PM
@mir0mik Sounds like a nice sunday plan :-) Thank you again!
mir0mik , 05-09-2020, 04:35 PM
@alberme96 Well more like upcoming week or month... More you starts to read more and more doors opens...
@alberme96 , 05-11-2020, 08:11 AM
@mir0mik great advice... thanks!
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