One other consideration that I left out concerning "non-60335" PSU. EMC.  Your 60950-1 PSU won't satisfy your LVD CE requirements in the EU after 2020 because it's being withdrawn.  If your client is forced to move to a new model PSU later then they should repeat at least the AC mains-related EMC testing as well at that time.  So unless you find a 60950-1 LPS PSU which comes with promises to support the LPS rating within 62368-1 for that same model in the coming year, then you should avoid 60950-1 and have EMC testing performed near-term with a PSU that promises a long life.

Carl

On 10/24/2019 12:25 PM, Carl Newton wrote:
Another couple of comments concerning your PSU choice:

I was told recently by a NRTL GMA pro that 62368-1 is not yet being accepted in China and Taiwan.  Accepted worldwide apart from those two at the moment.  So your global plans, if any, should be considered.

Also, I just recently encountered a PSU that is "certified" to 62368-1 with the output rated PS2.  Based upon the 90W output rating of the supply,  it appears to me that it's a mistake on the part of that manufacturer.  PS2 output power limit characteristics don't impose all of the safety criteria that Limited Power Source (LPS) compliance will require as described in 60950-1 and that rating will not provide you with the same latitude in your design that an LPS supply will (if your power requirements are about 90W or less).  It appears that 62368-1 is addressing this with Annex Q, which defines and accommodates an LPS output rating (backward compatible with 60950-1).  This is critical if you have a low-power device and need to avoid some enclosure/design characteristics.  So as you shop, if you find a 62368-1 supply that you like be sure to check whether or not it has the LPS output rating, as a capable 60950-1 supply would, if you have low-power requirement and want the design latitude that the LPS output rating provides.

Carl

On 10/24/2019 6:50 AM, John Woodgate wrote:

Since it works with a phone, 62368-1 applies. I would not rely on 60950-1 because of the incidence of fires and electric shock. Bedrooms and nurseries are especially sensitive locations. Also, note that a jack plug is shorted when inserting or withdrawing. That is why the concentric connectors are used instead on portables and everything else.  What happens if you plug the 5 V DC into a headphone socket, too? Not a good connector to use.

If the client insists on what appears to be a very marginally safe course of action, I think you have to consider your professional position.

Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associateswww.woodjohn.uk
Rayleigh, Essex UK
On 2019-10-24 11:34, Matthew Wilson | GBE wrote:
A client has a product, to be used by consumers typically in a bedroom or child's nursery, which has a microcontroller and is Wi-Fi enabled so it can present data to 'the cloud' and interact with a mobile phone 'app' to change some parameters on the device. We have been asked by the client with help in sourcing a power supply for it from Far East sources. They want a 'wall wart' type plug in device with a 2 metre lead to a jack plug. The product requires 5V DC up to 1A and has a jack socket DC input. Cost is, of course, a key driving factor but there are some very keen priced items available out of the FE.

Ignoring 62368-1 for now, as there is still just over a year to go before this becomes mandatory and it appears the majority of 'cost effective' PSU manufacturers are not up-to-speed with this standard yet. They probably will wait till the last minute, or relying on the 'get-out' 4.1.1 clause in 62368-1.

The question is what standard should the PSU meet? 60950-1 or 60335-1? 60950-1 is for IT equipment, 60335-1 is Household and similar electrical appliances. Both standards might apply. If it was a laptop power supply 60950-1 would even though the laptops are sold and used in the home.

One potential PSU manufacturer, however, does claim both 60950-1 and 60335-1 for the same product. Is that possible with one design?

I know this might also spark a debate about risks of FE manufacturers, conformity of production and so on like the excellent blog post here https://www.unit3compliance.co.uk/tag/power-supply/ We have a presence on the ground in the FE to verify any manufacturers and all the three potential suppliers identified so far have listings on TUV or Intertek and have also provided conformity documentation supported by legitimate third parties.

Any thoughts welcome.

Thanks for reading.

Regards,




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