<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">2014-05-26 16:10 GMT+02:00 Luke Kenneth Casson Leighton <span dir="ltr"><<a href="mailto:lkcl@lkcl.net" target="_blank">lkcl@lkcl.net</a>></span>:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div class="">On Mon, May 26, 2014 at 3:04 PM, <a href="mailto:mike.valk@gmail.com">mike.valk@gmail.com</a><br>
<<a href="mailto:mike.valk@gmail.com">mike.valk@gmail.com</a>> wrote:<br>
<br>
> That means that every USB3, slave, device must accept a USB1/2 link,<br>
> from a master,<br>
<br>
</div> yyyup.<br>
<br>
> USB3 requires 5 extra pins<br>
<br>
4 coming off the CPU Card.  what's the 5th one?<br></blockquote><div><br>Apparently: GND_DRAIN:
Ground for signal return<br><br><a href="http://en.wikipedia.org/wiki/USB_3.0#Pinouts">http://en.wikipedia.org/wiki/USB_3.0#Pinouts</a> <br><br></div><div>Probably it used to "drain" signal leakage from the SuperSpeed cable pairs. But how that is to be terminated on the devices properly, I have no idea. I'm not sure if it's necessary in the EOMA connector either.<br>
<br></div><div>Couldn't find anything useful on the Internet either.<br></div><div><a href="http://electronics.stackexchange.com/questions/107669/usb3-with-fewer-wires">http://electronics.stackexchange.com/questions/107669/usb3-with-fewer-wires</a><br>
<br></div><div>Just a notice in this one:<br><a href="http://www.onsemi.com/pub_link/Collateral/AND9114-D.PDF">http://www.onsemi.com/pub_link/Collateral/AND9114-D.PDF</a><br><br></div><div>Page 7: Quote on PCB design:<br>
"Place grounds between high speed pairs and keep as<br>much distance between pairs as possible to reduce<br>crosstalk"<br></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">

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