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| What is the motivation of intel to want PSUs that are 12V only? |
| << < (7/14) > >> |
| DBecker:
The opportunity for higher efficiency is using a single power rail. With a single power rail the supply doesn't have to handle the extreme of power drawn mainly on 3.3V (typical a few years ago), or primarily on 12V (e.g. a GTX Titan Z GPU on a system that otherwise is using 20W). The typical power-hungry chip is running at 0.9-1.2V. VRM efficiency drops like a rock with a buck conversion ratio of much over 10 (under 10% duty cycle), so 12V is at the upper end of the range. 50V is the 'safe low voltage' limit in some regions, so a European regulation allowing 75VDC (presumably the Low Voltage Directive LVD 2014/35/EU) isn't a design target for global products. 48V has been used in telecom for about a century, and thus was the natural choice for a DC server supply when that started being a requirement two decades ago. |
| amyk:
Two words: planned obolescence. Instead of putting the highly-stressed power semiconductors in a separate easily replaceable module, build them into the more expensive and difficult to repair motherboard so as to limit its lifetime and repairability. |
| OwO:
--- Quote from: NANDBlog on March 05, 2020, 10:41:24 pm --- --- Quote from: OwO on March 05, 2020, 04:19:06 pm ---Personally I would go with 70V. It's the highest I can still comfortably touch and at this level the higher the better. The DC-DC converter on the motherboard doesn't have to be transformerless. --- End quote --- Nah. There are only 28 buck converters from TI above 70V, with max current of 3A. There are over 240 with max voltage between 14 and 24V, with max current of 40A. And you dont end up with large ripple voltage and current, and big capacitors and inductors. 12V is a good compromise. --- End quote --- That's why I said The DC-DC converter on the motherboard doesn't have to be transformerless. You do not use a buck converter to go from 70V to 12V, you use a transformer and have plenty of topologies to pick from - isolated Cuk, forward, flyback, etc etc. Discrete synchronous rectifiers (ideal diodes) exist, and plus at this power level you could afford a CPLD controlled FET switch on the output side rather than diodes. 70V is what I would go with if I were designing a system for my own use and can disregard regulations, I consider it safe to touch. |
| Circlotron:
A 12V single output power supply would be a good starting point for a cheap bench supply too! |
| langwadt:
--- Quote from: amyk on March 06, 2020, 04:31:46 am ---Two words: planned obolescence. Instead of putting the highly-stressed power semiconductors in a separate easily replaceable module, build them into the more expensive and difficult to repair motherboard so as to limit its lifetime and repairability. --- End quote --- nonsense, it'll change very little on motherboard it already has loads of switching converters |
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