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PSU supporting both 120v and 240v.

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David Hess:

--- Quote from: wraper on June 11, 2019, 05:48:09 pm ---3. Just design so it works in wide voltage range. Quite easy with say flyback or forward converter topology.
--- End quote ---

That comes at a cost and performance disadvantage compared to doubling or not doubling the voltage at an earlier stage.  Some low power converters work that way though and of course universal input power factor correction stages do exactly what you suggest at high powers but they are not dealing with high transformation ratios.

wraper:

--- Quote from: David Hess on June 11, 2019, 06:28:27 pm ---
--- Quote from: wraper on June 11, 2019, 05:48:09 pm ---3. Just design so it works in wide voltage range. Quite easy with say flyback or forward converter topology.
--- End quote ---

That comes at a cost and performance disadvantage compared to doubling or not doubling the voltage at an earlier stage.  Some low power converters work that way though and of course universal input power factor correction stages do exactly what you suggest at high powers but they are not dealing with high transformation ratios.

--- End quote ---
Virtually all prone chargers work this way.

David Hess:

--- Quote from: wraper on June 11, 2019, 06:32:21 pm ---
--- Quote from: David Hess on June 11, 2019, 06:28:27 pm ---
--- Quote from: wraper on June 11, 2019, 05:48:09 pm ---3. Just design so it works in wide voltage range. Quite easy with say flyback or forward converter topology.
--- End quote ---

That comes at a cost and performance disadvantage compared to doubling or not doubling the voltage at an earlier stage.  Some low power converters work that way though and of course universal input power factor correction stages do exactly what you suggest at high powers but they are not dealing with high transformation ratios.
--- End quote ---

Virtually all prone chargers work this way.
--- End quote ---

Phone chargers are low power.

soldar:

--- Quote from: wraper on June 11, 2019, 05:34:26 pm --- About TV, maybe, if it's small or really old. As of Laptop PSU, there is 99% chance it has PFC, unless it's Chinese knockoff. How do you even know that? You cannot take apart laptop PSU in non destructive way as covers are welded together. Did you actually measure current waveform?
--- End quote ---
You are not responding to my questions. You are changing the subject.  Again: Where is the regulation that says appliances over 75W need to have active PFC? Where? Because I am not saying it does not exist. I am saying the regulation that I have already cited twice does not require it. And between IEC_61000-3-2 and your vague and unsupported assertions I am afraid I have to go with the former.

And, yes, I have opened my Dell 90W power brick as I discussed recently in another thread. You can find it easily.

Again, look, it seems you just want to argue for the sake of arguing. I am not saying I am right. I am just showing the evidence that I have but you contradict it without any evidence whatsoever. Just show me where it says active PFC is mandatory in the EU. I will be glad to see it and learn. Please show us the evidence. What regulation is it?

David Hess:

--- Quote from: soldar on June 11, 2019, 06:51:56 pm ---... Where is the regulation that says appliances over 75W need to have active PFC? Where? Because I am not saying it does not exist. I am saying the regulation that I have already cited twice does not require it. And between IEC_61000-3-2 and your vague and unsupported assertions I am afraid I have to go with the former.

...

Just show me where it says active PFC is mandatory in the EU. I will be glad to see it and learn. Please show us the evidence. What regulation is it?
--- End quote ---

The regulations do not specifically require PFC but instead specify a maximum input harmonic distortion for different power levels and classes.  Usually the most economical way to meet the specifications is to use active PFC although sometimes passive PFC is sufficient.

https://en.wikipedia.org/wiki/IEC_61000-3-2#Scope

Incidentally, industrial uses may be charged extra based on their power factor but doing this has been considered impractical for consumers so far.  So instead they regulate it on the supply side now.  It was not a big deal until switching power supplies became ubiquitous.

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