[Arm-netbook] EOMA68 Power Specifications

[Joseph Honold]

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.