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Posts: 2
Registered: ‎05-03-2016

CP2102N pin order - why?

[ Edited ]

I'm working on a two layer board using the CP2102N and was wondering why the pin order is the way it is. If you're using the standard pinout for a mini or micro USB connector, none of the pins on the CP2102 line up. The pin order doesnt allow you to cleanly route the D+, D- and Vbus pins between the connector and the CP2102. Everything gets all twisted up because you're forced to switch layers to route between pins. I notice the pin order is the same way on the CP2104. I cant be the first person whose been frustrated by this. Is there a reason the pin order doesnt match up? Maybe there's something I'm missing?

 

Thanks,

Rob

Posts: 2,384
Registered: ‎10-14-2014

Re: CP2102N pin order - why?

do you mean you prefer the pin sequence (pin 3, 4, 5, 8)changed from GND ->D+->D- ->VBUS to VBUS ->D- ->D+->GND.
WeiguoLu
Posts: 2
Registered: ‎05-03-2016

Re: CP2102N pin order - why?

Hi WeiguoLu,

Yes, that's the pin order that I'd think would make the most sense. See the attached drawing. It almost seems as if the chip designers went out of their way to arrange the pins in the exact opposite order, which makes me wonder if there is a preferred layout technique that would take advantage of this

 

Posts: 488
Registered: ‎02-21-2014

Re: CP2102N pin order - why?

Well, I guess you could always mount the chip on the opposite side of the board as the connector, lol.

 

But yeah, not sure why this is the case. I wonder, are the common pin arrangements for USB type B connectors (not mini or micro) the same? Maybe this is a hold-over from when that was the expected connector type...

Highlighted
Posts: 488
Registered: ‎02-21-2014

Re: CP2102N pin order - why?

Eh. I guess it would be still a little funky if the pin-out was changed to match the USB type-b mini/micro connections, if you were using a full-sized type B connector:

 

 

typeB.png

Not as funky as the current pin-out with mini / micro, though.

 

Posts: 3,153
Registered: ‎02-07-2002

Re: CP2102N pin order - why?

Even the pins of an SMD full-size type B are like the mini/micro connections. So unless SiLabs really thinks the chip and the connector belong on opposite sides of the PCB, they definitely made a weird choice.