I must be missing something but I thought the overwhelming majority of wattage is being delivered on the 12V lines which these units do not touch, especially because most of the 12V pins are in the 4 and 8 pin connectors and not the 24 pin ATX connector. Even the beefiest PSU doesn't have more than 120W on 3.3V and 5V and I bet most of that is intended for spinning rust disk usage and not for the motherboard. So ... why do we have 80W, 120W, 160W, 400W units...? What's the difference?
Power Supply Why do the PicoPSU and alike units have wattage rate?
- Thread starter chx
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Sigh. Let me reword then: why would it burn to death? Why does it handle different amounts of power? Once again: wattage is voltage times amperage and as far as I can understand these things, the amperage on all but the 12V lines are very low in a modern PC and these units merely pass the 12V line on. Or so I thought.
Just like a barrel connector just passes voltage and current, it's just a piece of metal after all, but can still burn to it's death if you go past it's rating....
PCB traces, mosfets, coils, they all have a physical limit to what they can handle.
PCB traces, mosfets, coils, they all have a physical limit to what they can handle.
Afaik this is how atx psu works: on power off the only active rail is 5vsb (sb=standby). Then on power on all rails is activated. This means switches. On smaller wattage mosfets is the king. Higher wattage, solid state mechanical relays. I'd venture to say there is no hard limit on SSRs mechanical relays only pcb traces and internal conductor used. But still there are limits. As long as you need to control it somehow there would be ratings.
On a little related note, how hard is it to search for something in the range of a certain wattage? Like, how would you know there is 330W brick on the market, instead of 300, 350 etc when what you actually need is something above 250? We're pretty much had to read the whole lineup.
Mod edit: Posts merged. Please don't double post, there's only 5mn between the two. Use the edit button instead
On a little related note, how hard is it to search for something in the range of a certain wattage? Like, how would you know there is 330W brick on the market, instead of 300, 350 etc when what you actually need is something above 250? We're pretty much had to read the whole lineup.
Mod edit: Posts merged. Please don't double post, there's only 5mn between the two. Use the edit button instead
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Afaik this is how atx psu works: on power off the only active rail is 5vsb (sb=standby). Then on power on all rails is activated. This means switches. On smaller wattage mosfets is the king. Higher wattage, solid state relays. I'd venture to say there is no hard limit on SSRs only pcb traces and internal switch used. But still there are limits. As long as you need to control it somehow there would be ratings.
On a little related note, how hard is it to search for something in the range of a certain wattage? Like, how would you know there is 330W brick on the market, instead of 300, 350 etc when what you actually need is something above 250? We're pretty much had to read the whole lineup.
Mod edit: Posts merged. Please don't double post, there's only 5mn between the two. Use the edit button instead
It is quite easy when you use Digikey or Arrow electronics. But sometimes things aren't perfectly categorized.
Solid state relays are usually mosfets. Solid State Relays is a logical description of a type of circuit. Mosfet is a type of physical component. Mosfets can have many uses, and solid state relays is one of them.
The SF600 gold actually uses a mechanical relay for example. An audible "click" can be heard when it is powered on.
Just relays.
SSR as the name states is just a relay without any mechanical movements. Can use quite a variety of components depending on the requirements.
In terms of current/volume it is a wash because the coils take up space as well as the enclosure.
It really isn't a matter of current that people pick one or the other.
Relays contacts are solid conductors so you don't deal with heat or voltage drop aside from what is already expected of the contacts. They are simple to implement and you don't need a printed circuit board. They are generally larger however, and the contacts may wear out or arc.
SSR are versatile and can be very compact for high current. However they produce heat and their effectiveness is limited when the ambient temperature rises (reducing the ability to shed heat). They usually require a circuit board, or built into modules like regular relays. They also drop a small amount of voltage.
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