On 08/30/2016 05:11 PM, Luke Kenneth Casson Leighton wrote:
Seems like there should be a minimum power requirement that all cpu cards and devices must meet.
okay - so you used the word "devices" which is not part of EOMA68 terminology. sorry i missed this, so didn't understand the question.
I spose motherboard is the correct term i should have used.
*from the perspective of the EOMA68 Cards* the *MAXIMUM* that they are permitted to use is 1.0A @ 5.0v
therefore...
*from the perspective of EOMA68 ***HOUSINGS*** .... * the *MINIMUM* that they must provide is: 1.0A @ 5.0v
Maybe I'm misreading the spec, but I don't see it specify that my motherboard must be able provide 5V 1A to the cpu card. That's the reason for asking this question.
above exactly 1.0A @ 5.0v, housings are ***REQUIRED*** to cut power without warning.
I don't see this in the spec either. Am I correct that http://elinux.org/Embedded_Open_Modular_Architecture/EOMA-68 is the 'official' specification for eoma-68? Or is there some other document?
This seems like a broken spec to me. Nothing in electronics is exact, so a sane spec should have a reasonable margin between the maximum current a card is allowed to draw and the point at which overcurrent protection is required to kick in.
appreciated - very good point this is the first time it's really been discussed. i'm already uncomfortable with the idea of having 5.0 watts in an enclosed space. 3.5 is okay. i _was_ thinking of raising the Housing limit to 5.5 watts, but was slightly concerned that people would abuse the extra headroom.
suggestions appreciated.... hmm... let me just add a section on the specification / discussion on the elinux.org talk page to reference this discussion...
Adding a section for power specifics would help clarify things.