XPost: alt.comp.hardware.pc-homebuilt, alt.comp.os.windows-10   
   From: nospam@needed.invalid   
      
   On Sun, 5/4/2025 2:14 PM, Mark Lloyd wrote:   
   > On Sun, 4 May 2025 00:43:41 +0200, Ivano Rossi wrote:   
   >   
   >> On Sat, 3 May 2025 17:04:01 -0500, Paul in Houston TX wrote:   
   >>   
   >>>>> Google:  Hyundai laptop power supply   
   >>>>>   
   >>>>> 12V, 2A   
   >>>>   
   >>>> That will only work if the company makes only one laptop power supply.   
   >>>> Does it?   
   >>>   
   >>> IDK.  However, if you search the internet, including the Hyundai   
   >>> website, you will only find the 12V, 2A or 3A models.   
   >>   
   >> Isn't 12 volts far too low for any modern laptop power supply?   
   >> Aren't they usually around 20 volts?   
   >   
   > The only recent laptop I've had that used 12V was the Asus netbook.   
   >   
      
   You can do VCore power conversion, off the +5V rail.   
      
   I have an AthlonXP board (A7N8X), where there was no ATX12V connector,   
   and the current came in through the ATX 20 pin main connector. Cylindrical   
   input inductor and three caps on the 5V side. Two iron core toriods on the   
   output   
   side and five electrolytics. Four MOSFETs, a pair per phase, knuckle draggers   
   with high gate capacitance. You don't run these on modern power supplies,   
   you go to the junk room and find one with a "strong" 5V output. While   
   gaming, the +5V consumption was high enough, it would cause most modern   
   PSU to shut off :-)   
      
      https://images.anandtech.com/reviews/motherboards/roundups/20   
   2/Q4/nForce2/asus/board.jpg   
      
   Four wires on the 20 pin connector, carried the current (13 amps plus).   
   There was a Richtek 50KHz converter,   
   and there were some "beefy" MOSFETs on there. And somehow, there   
   was enough gate swing, to turn those MOSFETs fully on and fully off.   
   And that powered a 65W processor. Normally, an estimate of a "good"   
   power rating for a phase on VCore, is a target of 30-35 watts,   
   so from an estimation perspective, you would expect to find   
   two phases on such a design (for 65W).   
      
   The board designs switched to ATX12V right after that, and suddenly   
   RichTek wasn't the only game in town.   
      
   Most power converters (SMPS) have run at higher frequencies   
   than 50KHz. The record holder, is the Haswell FIVR inside the   
   CPU package, running its power converter at 200MHz. Nobody   
   else has some close to being that bold, since.   
      
   The designs today, are rather cheesy. There are some "favored" MOSFETs   
   for PC design. You use a shitload of those, for no particular reason.   
   Some of the designs run hot. On the Asus side, they did a multi-phase   
   design, where they had *three* banks in parallel. That's three phases   
   with exactly the same timing and firing point, and the currents from them   
   add. That wouldn't be necessary, if you spent a buck or two more   
   on a better MOSFET. But I have to admit, I'm impressed with the   
   temperature rise that gives. Lukewarm  when flat out at 200 Watts.   
   There is as much heat coming from resistive loss in the PCB, as in the MOSFETs!   
   There is likely more VCore ripple on those boards, but there is   
   no sign of instability that I can see.   
      
   For that board, an electrical type set up a go-fund-me, to buy a small   
   multi-channel scope, so he could take pictures of the phase firing order,   
   and prove what they were doing :-) Which is also a cool aspect of our   
   current time. Donation-ware reverse engineering.   
      
      Paul   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)