0
\$\begingroup\$

We have developed a docking station product which charges multiple devices simultaneously, and currently ships with a 5V, 3A barrel jack adaptor. We are looking to move this over to USB power, and have recorded maximum current draw with a full complement of devices around 1.8A (quickly returning to 1.5A, which I understand is the minimum required for a USB Dedicated Charging Port).

The factory are telling me that if exceeding 1A it will not pass CE certification, but I can find no reference to this in any of the documentation I have read, so my question is:

  • Is the factory correct? If so, could anyone refer me to a standard which states this?
  • Given the prevalence of USB supplies with 2A or greater rating, would we be violating any rules by simply stating in the manual that it must be connected to a supply which can provide 2A or greater?

Thanks in advance.

\$\endgroup\$
  • 2
    \$\begingroup\$ It might be that some component involved can't handle the higher current. Wires or connectors etc. In which case there might be a fire hazard. \$\endgroup\$ – Lundin Jan 9 at 9:53
1
\$\begingroup\$

CE marking and USB standard are completely different to each other. CE is for safety, USB is functionality. So this is at least two different questions.

No idea what the factory is quoting the 1A limit for CE. Ask they for what standard this breaks, they should know, that's what you're paying them for. CE is a lot more worried about EMC, EMI and voltage limits rather than a current value. Assuming you've done a good design, EMC and EMI should be fine (and they'll give you a report of emissions), and USB is 5V (unless you're doing some of the higher power chargers).

As for the current question about USB, no rules are broken if you don't claim to be USB certified. But be aware, many users don't know about current out of USB, so will claim your device is broken when it doesn't work. This is why the Amazon Echo comes with a dedicated USB supply, as they clearly state that you have to use their USB supply due to the higher current capability of it.

\$\endgroup\$
1
\$\begingroup\$

I think the factory is confusing CE marking with USB specification.

CE marking is purely a safety certification, meaning that any test made on the product are there to certify that the product is safe to use.

The only place where you will find the USB specification is on the USB consortium website, and here you will find the specified limits for current consumption.

Complying to the USB specification is just the first step, after that, you need to comply to the CE marking standards, which will look at the electrical safety of the product, e.g. It won't catch fire when you start to draw 2A.

What I think the factory means, is that if you are doing a design change on a CE certified product, you will have to re-certify it, so make sure you are still within the EMC rules and electrical safety defined by the standard. The amount of test you will have to put the new hardware through, depends on how big are the changes compared to the previous version.

\$\endgroup\$
1
\$\begingroup\$

If your device doesn't have a captive lead, (at least in some jurisdictions) you will need to have some mechanism to handle the case where someone uses a different, USB certified cable to connect your PSU to your device.

If you're pulling 1.5A through a cable designed for 0.5A you'll be looking at a fire.

The usual tricks are to check the droop along the cable using the shield for reference (but be careful of cables which lack one), or just shutting down if the supplied voltage droops.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.