Layout around USB

[Rajinder1268]

Hi all,
I have a USB connector, that I am connecting the shield via a OR to the GND on my PCB.
Do I just connect the 4 shield pins together and route them to one side of the 0R and the other side of the OR to GND? Or do I need to have a GND plane underneath the connector obviously avoiding the four shield pins?

What is the recommended method?

My second question is that the D+/D- lines going out from the connector are crossed on the pins of the FTDI chip. How can I sort this out? I only have a 2 layer PCB? I was trying to avoid putting VIAs in the GND plane underneath the D+/D- signals.

Thanks in advance.

 

[wwfeldman]

i don't know, but maybe you can explain this line:

I have a USB connector, that I am connecting the shield via a OR to the GND on my PCB.

does via an OR mean your connecting the shield to the input of a digital OR gate?
that makes no sense to me.

shields are usually connected to ground
details on how and where to do that depend on the details of your device.

as for this:

Do I just connect the 4 shield pins together and route them to one side of the 0R and the other side of the OR to GND? Or do I need to have a GND plane underneath the connector obviously avoiding the four shield pins?

i would have thought that all four shield pins would be connected to the ground plane that goes under the connector
the only things that are avoided are the four pins of the USB bus.

My second question is that the D+/D- lines going out from the connector are crossed on the pins of the FTDI chip.

FTDI manufactures (at least) 56 different chips.
it would probably help if you specified the part number of the FTDI chip

 

[ZASto]

I see no reason to connect shield via zero Ohm resistor (0R).
0R resistor is same as connecting straight to GND. (Just one more component that can cause more headache )

 

[Rajinder1268]

Hi all,
I have asked the manufacturer of the FTDI device FT232 and that is what they recommend. A low impedance path to 0V, the 0R resistor can be removed, connected or replaced by a ferrite or capacitor.
Thanks in advance.