TUSB1002: S-Parameter measurement

Muqi

Part Number: TUSB1002

Hi all,

I got a problem when trying to measure the S-Parameter of the channels of chip TUSB1002.

In the datasheet, there are some S-Parameters measured by TI. But when I wanted to do this, I found that the chip wouldn't power on to work in U0 mode if it was connected to VNA. It seems that the chip's channels can only be turned on when certain USB signals are detected. Thus, how can I measure the S-Parameters using a VNA?

I did some simply test using the evaluation board. If the mode pin is 0 (one of the reversed mode), the chip will keep drawing some current. Otherwise, the current level is relatively low, which indicates that the channels are not turned on.

over 8 years ago

0 Diego Cortes over 8 years ago

TI__Mastermind 36085 points

Hello Muqi,

You need to connect both RX differential pairs to 50Ohms single ended terminations. Our re-driver is constantly checking the presence of these terminations before establishing any connection. Please see the USB3 specification for a detailed description of these terminations and how to connect them.

Regards,

Diego.

0 Muqi over 8 years ago in reply to Diego Cortes

Prodigy 50 points

Hi Diego,

Thanks for your reply.

I'm wondering if you have any idea that the checking can be disabled or keep the re-driver always work in U0 mode?

Thanks a lot!

Muqi

0 Diego Cortes over 8 years ago in reply to Muqi

TI__Mastermind 36085 points

Hello Muqi,

You only have to present the termination resistors on the RX differential pairs, on the Host side you already have them, thanks to the TX termination of the Host, just connect the terminations on the other side and that's it.

Regards,

Diego.

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TUSB1002: S-Parameter measurement