Quote from: Inspector 2211 on February 04, 2012, 12:03:22 AM

Quote from: ArtForz on February 03, 2012, 11:45:16 PM

My early LX150 miner prototypes had a 60A switcher for vccint for 8 chips -> 7.5A each... and that later turned out to be not enough.

So, how come the German guy (Stefan) of ZTEX gets by with a [very compact] 8 Amp converter for VCCINT?
His dynamic clocking now achieves > 200 MH/s on a -3 device.
Impressive.
(Even more impressive considering the fact that he has less than half of the Xilinx-mandated amount of bypass capacitors surrounding the Spartan-6.)

Quote from: ArtForz on February 03, 2012, 11:45:16 PM

Btw, one thing that made me go WTF when looking at interior pics of copacobana a few years ago... a single massive AC->1.2V converter for vccint and really heavy cables + busbars to route it around...

Here's a picture: http://www.copacobana.org/photos/photo_b4.jpg

Well, 7.5A/core was ok for a 192-205MHz 122-round 2-stage-per-round pipeline design. Just my later designs needed more power.
Also, unless I misremember, he uses ultra-low-esl 0306 caps for vccint, xilinx recommended #s are for caps with ESL values similar to 0402s... so... prolly fine.
Yep, that's the picture... Still don't get why on earth they did it that way. A AC->12V PSU and half a dozen or so point-of-load converters would've saved a whole lot of copper (and prevent accidentally welding holes in your chassis...)