# +12V/+5V load proportions for testing group regulated units

• 07-22-2013
rafal_iB_PL
+12V/+5V load proportions for testing group regulated units
How are/should be loads on these rails selected in progressive tests to evaluate stability of group regulated units?

For example, if we have 500W group regulated unit with 432W of 12V capacity and 120W 3,3/5V combined, how should loads be picked?

Both 432W 12V + 68W 5V/3,3V and 380W 12V + 120W 5V/3,3V and 406W 12V + 94W 5V/3,3V (halfway between first two) are valid as far as load distribution is concerned, yet will produce very different voltage readings. There may also be a set of progressive loads which will produce zero drop on either of rails, but does this mean group regulated unit has perfect regulation on said rail? I don't think so.
• 07-22-2013
Philipus II
For standard load testing I use the 80Plus methodology. I've read the official testing guidelines and put the formula into Excel.
• 07-22-2013
McSteel
Well, each PSU model (I should go so far as to say each sample) has a (slightly) different crossload pattern. Short of doing what some of the reviewers already do - applying a "full spectrum" crossload pattern (crmaris, makalu, Zhuoke, SiYu, and some others) - you can't be sure what the best (most fair?) approach is.

Do you emulate a "typical system"? Or perhaps decide on some fixed percentages of maximum ratings for each rail? Or maybe a fixed ratio between 5V and 12V load..? Whichever you choose, you can't be called out on it, if you keep your method and decision consistent.

Personally, I'd use a fixed ratio of 6:1 in favor of 12V. Then I'd not be lazy and do two more tests, one with a fixed 5V load and progressive 12V, then one with a fixed 12V and progressive 5V. This would probably be overkill in some ways, but it would also paint a clearer picture of the PSU's "character".