Electronic – non-isolated power supply safety demand

accepower

We are designing a power supply for a MCU design, which must run directly from mains 230VAC.

We have previous used a "traditional" 230VAC to 6VAC transformer, and used a simple bridge capacitor solution to generate DC supply.

The solution we are working with is the bp5048-15 from ROHM, which would do the job.

www.rohm.com/products/databook/pm/pdf/bp5048-15.pdf

But since this is a non-isolated solution, we get the mains supply to be common with the PCB ground. Which possible could be dangerous, if PCB ground is exposed.

We want to sell this product in Europe in the future, and therefore we need a CE approval.

The CE directive on high-voltage (>48V) is pretty complicated.

What are the safety demands when designing this kind of circuit?

Can it be done non-isolated, or is this a hard way to go?

Best Answer

To expand on what Martin said, you can also buy pre-certified "power bricks" that are like the wall wart except are intended to be internal to your unit. Most of these nowadays handle universal line power in. You provide a universal line cord socket on your unit. That connects only to the power brick with a fuse in series. The other side of the power brick provides isolated and regulated DC.

The power brick market is very competitive. These bricks don't cost much more than a big iron transformer to handle the same power. Mean Well, Astec, Artesyn, and CUI are just a few companies in this space that come to mind. Do a little digging and you can find more.

 

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