SP3 power adapter pins

[ericpelleg]

I would like to make some noise for a USB hub via the power port. I've always wondered why there were 6 pins per side on the power connector of the SP3. I've been secretly hoping the power brick actually does more than supply power via the usb port, and is in fact a true USB data port to be enabled in a future firmware update.

I've been looking, and even searching on this forum for an explanation, or even a guess about why the simple AC adapter has as many pins as it does. Does anyone have any ideas?

 

[zhenya]

The power port is used also for docking, so it has pins for power, usb data, audio, and video.

 

[ericpelleg]

The power port is used also for docking, so it has pins for power, usb data, audio, and video.

Right, but why does a simple power cable need 6 pins (per side) to output a simple 12V if the brick wasn't intended to carry data?

 

[zhenya]

Ah, I see what you are saying now. Can't say I know. It would sure have been nice if they'd connected them to the usb port they have in the brick - making it functional for charging and data!

 

[GreyFox7]

Hmm, thought Id seen the pinout on the power connector somewhere but cannot find it. However lets start with the old connector which like this one is reversible, that means what ever is on one side is duplicated on the other and on both ends. the old connector had 5 pins - + x + - its a palindrome, either way you plug in it its the same.

With the blade connector when you turn it over the top is now the bottom and the bottom is the top as well as reversed end to end. so... if 3 pins are + x - at the very minimum 3 pins on the opposite side and end must be the same. Now if they just duplicated them for redundancy that's all 12 pins. From examples of other power brick connections the center x pin may be a control pin. With this plausible pinout we never touched USB at all.

Not saying that's what they did but it's possible.

 

[bluegrass]

There are pins on both sides so the power pak can be plugged in with the cable going up toward the top of the Surface or down towards the bottom. Power needs two of the six pins on each side so it can be plugged into the Surface two ways. The other 4 or 8 if you count both sides are connected to the Surface's bus because the docking station functions for video, audio, USB2 & 3 plus Ethernet. Remember the old days when you use to plug in boards into a towers bus. I'm sure the docking station has an extension of the Surfaces bus so that it can add peripheral to the Surface's bus. I doubt that Microsoft has made available the pin outs for owners of the Surface. At least I've never seen a technical manual that can be downloaded for it.

 

[GreyFox7]

USB requires at minimum 4 pins [ + D+ D- - ] two power and two data. if you used 8 pins for USB (duplicated) then you only have 4 pins left to charge the Surface and you would have to eliminate the control signal. I don't think they would have done that.

If you said hey I only need USB data signals then potentially you could configure it that way with Power and Data on opposite sides at each end of the connector but again I don't think they would do that.

Note if you look at the connector in the Surface you see its bristling with pins all the way across not just the six at the ends. This is what the Dock uses to connect everything.

 

[zhenya]

Great explanations. I guess though that only partially answers the question, as adding the usb data lanes would have just required making the blade portion a little wider, which doesn't look like it would have posed any problems.

 

[olimjj]

Actual Pin out Configuration
G 12V DET 12V G SP1, SP2 Plug

Speculated Pin out Configuration
G 12V DET__________DET 12V G SP3 plug
Reason for a 6th Contact is the physical separation of the DET pin. Separation was possibly needed for engineering design, cross pin interference, alignment considerations, stability etc.. (just guesses)

The duplication of the pins on both sides of the Plug is most likely to handle electrical loads and for a more contact area and stability.

Conclusion:
There are basically the same as the original in function with no obvious additional capabilities.

 

[olimjj]

I inadvertently omitted the most likely reason for the substantial physical space of the DET contacts on the plug. This is were the SP3's jack internal contacts supply the additional functions when mated to the dock station connector. This give rise to a possible future power supply plug iteration, maybe on the SP4, which could provide data lines for the USB port on the brick; or for future peripherals. Am I dreaming or do I have a keen sense of the obvious?

 

[GreyFox7]

I inadvertently omitted the most likely reason for the substantial physical space of the DET contacts on the plug. This is were the SP3's jack internal contacts supply the additional functions when mated to the dock station connector. This give rise to a possible future power supply plug iteration, maybe on the SP4, which could provide data lines for the USB port on the brick; or for future peripherals. Am I dreaming or do I have a
keen sense of the obvious?

Sorry you've completely lost me.
So now I have to ask... did anything I posted above make sense to you or are we both just blowing in the wind?

 

[olimjj]

@GreyFox7 If you look at the PLUG on the power supply and my speculated pin-out it correlates with your description. The separation space in the middle is the reason why they put 6 pin contacts on the plug ( 12 if you count both sides) instead of the 5 on the plug of the SP1 an SP2. They had to put in the space because that area inside the SP3 jack has additional contacts for he Dock Station connector, which the power supply does not utilize( at least not yet). Have I managed to add additional confusion.