I have come to believe that a PSU which has no voltage selector at the back and can operate from 100Vac to 240Vac most probably has PFC circuit inside. I dont know how true this assumption is (not true for mobile chargers) but all the ATX SMPS I have with me are like this.

There is a seconds sale of a particular PSU right now, I am thinking of buying it in some quantity. But I am not able to know if it has PFC or not. No documentation seems to be available online. Can you please look at the attached photos and guess if it contains a PFC circuit ? Based on some photos I found online I know it has this ic TNY277, I dont know if it is for PFC or not.

 

As it is CE marked, it must meet EN61000-3-2 (Harmonic Currents), which have reasonably strict limits for computer equipment (not as strict as lighting) so, at a guess, it will have some sort of power factor correction.
However, it is perfectly possible to make a flyback converter without PFC that operates from 90V to 250V.
TNY277 has a maximum output of about 20W, so that's not the main controller chip.

 

TNY277 is just a switch with a feedback input for undervoltage on the output of a flyback converter. There is no mention of doing PFC in the datasheet. At least none that I could find.

 

Output is 210W, so when powered from 240V current is expected to be about 1 Amp.
Input current on the table is 2.5 Amps so no PFC provided

 

Output is 210W, so when powered from 240V current is expected to be about 1 Amp.
Input current on the table is 2.5 Amps so no PFC provided

It belongs to class D "Personal computers. . ." so its maximum 3rd harmonic current is 3.4mA per Watt of input, so I think it would need PFC.

 

It belongs to class D "Personal computers. . ." so its maximum 3rd harmonic current is 3.4mA per Watt of input, so I think it would need PFC.

Some ATX-PSUs come with no PFC. I have a few of them. I have compared both, the non-PFC one pulls 25% more current for the same task executed on the same computer. This thread originates from this dilemma. If I can have PSUs with PFC then I can buy smaller UPS and thus save some money.

 

Some ATX-PSUs come with no PFC. I have a few of them. I have compared both, the non-PFC one pulls 25% more current for the same task executed on the same computer. This thread originates from this dilemma. If I can have PSUs with PFC then I can buy smaller UPS and thus save some money.

It might take more current, but does it take any more power?

 

Take in mind inrush current , when the PSU is powered

 

It might take more current, but does it take any more power?

Hmmmm .... valid point. Unfortunately I dont have a power meter at the moment.