Curious why you couldn't (or don't want to) use a 19V AC-DC Internal Adapter? Rather have 12V?
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I believe they said this unit took a 12V input.
Aside from that, it's more efficient to get a 12V input since that's the most used voltage rather than creating heat converting a voltage you can't use to one you can.
Got it; thanks for explaining. Between two quality high efficicency adapters (12V and 19V) is it really that much a difference thermal wise with such efficient AC-DC units?
Wall current to 12V is slightly less efficient that wall current to 19V (which is slightly less efficient than wall current to 24V, etc.) If you look at the spec sheets for the Meanwell RPP units from 12V to 24V is maybe 1.5-2% difference in efficiency. Where 12V wins out over 19V or 24V is you don't then have to do a second conversion to 12V at the DC-DC level. I
f you have a 12V input from the AC-DC unit, the only conversion that needs to happen is 12V to 5V and 3.3V. These are comparatively small since the vast majority of current flowing to the motherboard and PC componentry is 12V. The main reason 19V is even a thing in the DC-DC market is that because of laptops, there is a massive selection of 19V DC bricks on the market. Conversely there are very few 12V options, especially at higher wattages. The reason 19V works with laptops instead of 12V has to do with how the battery charges and discharges I believe.
I think the ideal solution would be wall socket to 12V and then a 12V DC-DC board. Alternatively if there was a way to do a wide input 12-24V DC-DC board, then we would have all of our bases covered. I know that Mini-Box has a 12-32V Pico, but it is low wattage.
http://www.mini-box.com/PicoPSU-80-WI-32V
My hope is in the next year or two to get FinSix to produce a 300-400W AC-DC that outputs 12V, but that is just a pipe dream at this point.
f you have a 12V input from the AC-DC unit, the only conversion that needs to happen is 12V to 5V and 3.3V. These are comparatively small since the vast majority of current flowing to the motherboard and PC componentry is 12V. The main reason 19V is even a thing in the DC-DC market is that because of laptops, there is a massive selection of 19V DC bricks on the market. Conversely there are very few 12V options, especially at higher wattages. The reason 19V works with laptops instead of 12V has to do with how the battery charges and discharges I believe.
I think the ideal solution would be wall socket to 12V and then a 12V DC-DC board. Alternatively if there was a way to do a wide input 12-24V DC-DC board, then we would have all of our bases covered. I know that Mini-Box has a 12-32V Pico, but it is low wattage.
http://www.mini-box.com/PicoPSU-80-WI-32V
My hope is in the next year or two to get FinSix to produce a 300-400W AC-DC that outputs 12V, but that is just a pipe dream at this point.
It's also a matter of having a robust connector and having the correct gauge to support it. 12V requires much more current than 19V. Most of those things become a non issue if you're doing an internal PSU build.
I wish we could get rid of that stupid 24pin connector. That's my pipe dream.
OEMs are already doing it, I've seen several Dell and HP desktops that have 8-pin connectors carrying just 12V to the motherboard.
Now whether we'll see the ATX standard ever switch is another matter.
That kind of blows, not having any 12V AC-DC unit specifically for these tiny 12V PSUs.
Unless you go a more DIY route with a switching power supply, but those are still too big to put in the smaller cases.
The Meanwell PSU is pretty small. 200W at 50mm x 100mm x 38mm. Unless you're talking about a high-tech design, it's about as size efficient as you can get. Even 200W bricks can't compete with that.
Can you link me to this particular PSU? All the Meanwell PSU's I've found for this wattage are 215 X 115 X 30mm so maybe it's from some other series that I don't know of.
The Meanwell EPP series goes from 75W all the way up to 400W.
The 300 & 400W units are 127mm x 76mm x 32mm while the 200W unit is 101mm x 51mm x 29mm.
http://www.mouser.com/Search/Refine.aspx?Keyword=Meanwell+EPP&Ns=Output+Power|1&FS=True
The 300 & 400W units are 127mm x 76mm x 32mm while the 200W unit is 101mm x 51mm x 29mm.
http://www.mouser.com/Search/Refine.aspx?Keyword=Meanwell+EPP&Ns=Output+Power|1&FS=True
Woops, 29mm... smaller than I remembered. You also have to add about 3mm for the soldering clearance. My EP300 PSU measures 36.3mm height to account for the soldering and bottom board components.
The convention in the PC world is 19V because it is the optimal charging voltage for Li-ion batteries. Because there are so many options out there for 19V bricks and presumably the technology is already there for smaller and more efficient 19V bricks, I think the small desktop units are merely following suit. I don't know if I'd call it stubborn on the OEM's part, they're merely reusing technology they've already spent the money to develop.
THanks for explaining it Lamp
My main concern regarding efficiency wasn't so much how efficient specific conversion are. I'm not qualified to say how efficient each voltage is. All I know is that there is a loss every time you have to convert a voltage, so AC to 19VDC to 12VDC is naturally less efficient than AC to 12VDC just owing to having one less step (add another step for 5VDC and 3.3VDC).
Also, with that in mind; I keep wishing there was a company that made an AC-DC PSU and acccompyaning DC-DC PSU and let you plug a battery in between the stages since UPSs incure a fair bit of loss converting DC voltages in the batteries to an AC output just so the computer PSU can convert it bact into DC voltages.
I think ATX is overdue for an update. Having motherboards take only one voltage and convert the others onboard would be great. We already see something like that with Thin ITX with takes 19V in and is required to convert enough power of other voltages to power a display and as many drives as there are data ports for.
The server market is ahead in that game. The companies large enough to have custom systems tend to already have motherboards that do this, and I hear Google even has servers with a battery backup on the motherboard.
True.
It's perfectly fair to have a small DC-DC PSU designed to use a widely used voltage when it's designed to use an external power brick. I just think it's a missed opportunity when you are geared towards desktops to not use the voltage most common in the target system especially when you do make internal solutions as HDPlex does.
I think if we're looking for maximum efficiency, 12V will be by far the better choice going forwards. While 12V AC-DC conversion tends to be less efficient than 19V, I'm pretty sure the DC-DC board would only need to convert the 3.3V and 5V currents which it would pretty much have to in either case. Assuming close to 100% DC-DC efficiency when being fed a pure 12V current, you're looking at a 5-6% improvement in overall efficiency in this case.
24V makes no sense.
19-20V would make sense to run everything off of, but that's less likely than for ATX to adopt a smaller, more condensed power input connector.
19-20V would make sense to run everything off of, but that's less likely than for ATX to adopt a smaller, more condensed power input connector.
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