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alediben

USB Type-C for JTAG SMT2-NC

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Hi, I'm working on a project based on a Xilinx Ultrascale+. The final board will contain, for JTAG interface, a SMT2-NC device with a USB type-C receptacle. This board should work as "device", and so as Upstream Facing Port (UFP). At the moment, I know how to treat the CC lines (via 5.1 kOhm pull-down resistors) but I still don't understand how to connect (or how to use) the VBUS lines, because the SMT2 is powered from the 3.3V and VREF pins and not VBUS.

Can I leave the VBUS lines unconnected or I should follow some specific procedure to connect them?
 

Thanks

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Hi @alediben,

I heard back from the other engineer. They said that since you are considering the SMT2 rather than the SMT3 VBUS does not need to be connected to the module. However, they mentioned that the USB 2.0 specification has an inrush current requirement and as a result, an associated minimum bus capactiance for a usb device and recommended placing a 1.0uF or 2.2uF (10 volt or higher rated) ceramic capacitor between VBUS and GND near the connector, even if you don't intend to draw power.

Thanks,
JColvin

 

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Posted (edited)
8 hours ago, JColvin said:

Hi @alediben,

I heard back from the other engineer. They said that since you are considering the SMT2 rather than the SMT3 VBUS does not need to be connected to the module. However, they mentioned that the USB 2.0 specification has an inrush current requirement and as a result, an associated minimum bus capactiance for a usb device and recommended placing a 1.0uF or 2.2uF (10 volt or higher rated) ceramic capacitor between VBUS and GND near the connector, even if you don't intend to draw power.

Thanks,
JColvin

 

Thank you very much, maybe I also evaluate the SMT3 (I've seen that it has a VBUS_DETECT pin). Is this compatible with the Ultrascale+ Architecture?

Edited by alediben

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