27 lines
1.8 KiB
Typst
27 lines
1.8 KiB
Typst
#import "@preview/acrostiche:0.3.1": *
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#init-acronyms((
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"PSU": ("Power Supply Unit","Power Supplu Units"),
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"PCB": ("Printed Circuit Board",),
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))
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= Exploration of the retrofitting of HP Power Supplies to EET
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The objective is the build a proof-of-concept for using an EET capture card on the 12V rail of a server #acr("PSU") without changing the form factor.
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The targets are as many HP server-grade #acr("PSU") as possible.
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At the time of writing this note, we have access to three #acrpl("PSU"):
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- // fill with infos
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= Current Share ISHARE pin
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Because the server #acrpl("PSU") are tightly integrated, it is very difficult to tap into their 12V rail.
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The difficulty comes from the fact that the current gets generated directly on the #acr("PCB") and is not carried over a wire that we can cut.
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Cutting a trace of tampering with the #acr("PCB") is completely out of the question.
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Fortunately, server #acr("PSU") have a feature called ~Current Sharing~ that enables using multiple sources to provide more current to a system.
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The simplest implementation would be to connect multiple #acr("PSU") in parallel to the same 12V rail.
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This solution is presented to be non-robust by many sources although they all recomend to use an external system that share the load between the sources, which is exactly what this solution is doing.
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In any case, the server #acr("PSU") often include an analog output that is proportional to their current and enables an external circuit to adjust their voltage based on their current to spread the load.
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This analog output can also serve as an information source for remote monitoring system.
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The actual reason why this output is there remain somewhat hidden but the important fact is that the #acrpl("PSU") provides us with their current information, which is all we nned.
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