RE: Simple analog signaling for an AC adapter
If a power supply has provisions to do the full communication, I do not think
that it will be much more expensive to also make it suitable for simple devices.
If the power supply has a complete digital interface on the secondary side
to communicate with a sophisticated device, it should hardly cost anything
more to detect that a simple resistor is in the device that is being powered.
It can be done with the same pin in the IC in the adapter.
On the other hand, if you have a simple device that does not have any fancy
stuff inside and just needs a certain voltage, you need to add a lot of costs
(an extra IC) to make it communicate with an adapter that can only work
with full communications.
The idea is that a customer has one adapter for several devices. So do we want
to make one adapter a little more expensive, or do we want to make several
devices much more expensive?
Arjan
-----Original Message-----
From: upamd@xxxxxxxx [mailto:upamd@xxxxxxxx] On Behalf Of Tomlins, Garry
Sent: Wednesday, December 08, 2010 1:20 PM
To: Piotr Karocki; upamd@xxxxxxxx
Subject: RE: Simple analog signaling for an AC adapter
I agree with Lee and Arjan:
This is heading down a path of unnecessary and complex functionality that leads in turn to a complex and expensive implementation. I beleive it will not be attractive to the major equipment ODM's who will need to adopt this if it is to be a success.
We should have a simple analog low cost option.
In my experience in servicing the adapter market for high volume electronics adding a pin, a wire, a resistor a pin to an IC is a big deal - let alone a separate communications system!
My vote is for a simple analog option as described. I believe this will have a good chance of adoption and would be a success for the project.
Garry
Texas Instruments (Cork) Limited, Registered in Ireland under Registration Number: 294554, Registered Office: Riverside One, Sir John Rogerson's Quay, Dublin 2
-----Original Message-----
From: upamd@xxxxxxxx [mailto:upamd@xxxxxxxx] On Behalf Of Piotr Karocki
Sent: 08 December 2010 11:50
To: upamd@xxxxxxxx
Subject: Re: Simple analog signaling for an AC adapter
I don't agree with Arjan.
We could either "describe current situation" or "shape the future".
Our standard could allow resistor-based "communication", something, something, and full communication (required voltage etc.).
But as one of goals is to allow to connect every device to every supply (and, in near future, connections in form of grid; power hubs, power storage etc.), every supply has to have full communication option. Making provision to understand simpler communication (as resistor based) makes supply more costly.
Say, we have hundred million devices. Half of them - resistor based communication, and tenth of them - full model of communication (4/10 of them some 'in-between' form).
Or, we could force whole 100 000 000 devices to have full model of communication.
But it is the only way to make this full communication cheaper - as it would be "more mass" production. It would be ONE standard...
And the only way to make possible to connect device from 2010 to power supply from 2050 or vice versa. This scenario is not impossible - when standard becomes "grid version"... How often you change wiring in your house?
________________________________
From: upamd@xxxxxxxx [upamd@xxxxxxxx] On Behalf Of arjan strijker [arjan.strijker@xxxxxxx]
Sent: Wednesday, December 08, 2010 12:26 PM
To: Atkinson, Lee; Bob Davis; upamd@xxxxxxxx
Subject: RE: Simple analog signaling for an AC adapter
I agree with Lee that UPAMD should also support low cost devices.
A simple resistor to ground inside the device could tell the adapter what voltage it requires.
More sophisticated device can still do power negotiation etc.
With regards,
Arjan Strijker
From: upamd@xxxxxxxx [mailto:upamd@xxxxxxxx] On Behalf Of Atkinson, Lee
Sent: Wednesday, December 08, 2010 12:08 AM
To: Bob Davis; upamd@xxxxxxxx
Subject: Simple analog signaling for an AC adapter
Bob, here is a quick presentation on the method that HP uses for signaling from the adapter to the notebook. We've had this system in place since 2005 or 2006, and have shipped maybe close to 150million systems that use the common "HP Smart" system (including notebooks, all in one desktops, and small form-factor desktops).
My suggestion is that we at least baseline a system that will allow some scalability of the communication method; at least, allow very low cost devices to connect to a UPAMD power source and work reliably even if their functionality is limited. I'm not sure that a lot of simple devices that would use UPAMD have a need for all the messages that the adapter could provide, or would be able to negotiate variable power consumption. I think we all agree, there is very little precedence for using sophisticated signaling in the common DC powered devices now in the market. Though I agree the simple methods are limited, if we can deliver a scalable solution there will be fewer reasons for the industry to not adopt UPAMD.
Thanks again--Lee