TUSB217-Q1: Meaning of "Pre-Channel"

Atsushi Hirai

Part Number: TUSB217-Q1
Other Parts Discussed in Thread: TUSB217

Hi team,

My customer is using TUSB217-Q1 in Host side application to redrive the "receive signal" at the host controller IC transmitted from an USB device connected through a 5m cable.
I read below apps note. It mentions the definition of Pre-channel is between host and TUSB217. In my customer's use case, it should be understand Pre-channel is between transmitter(USB device) and TUSB217, is it correct?
Please advise.

www.ti.com/.../slla451.pdf

Regards,

over 3 years ago

0 Malik Barton57 over 3 years ago

TI__Guru 64326 points

Hi Atsushi,

Your understanding is correct, from a device perspective the pre-channel is in between the device transmitter and TUSB217.

0 Atsushi Hirai over 3 years ago in reply to Malik Barton57

TI__Expert 3630 points

Malik-san,

Thank you for your reply! Understood.

But in that case, the boost level may be set to 2 or 3 and, it may be too strong for host transmitter and the near-end mask.

Should my customer search the best boost level and RX sensitivity to keep good balance between host transmitter and device transmitter?

Regards,

0 Malik Barton57 over 3 years ago in reply to Atsushi Hirai

TI__Guru 64326 points

Hi Atsushi-san,

That is correct you want a balance between host and device. Typically it is best to tune boost for the direction with the most pre-channel loss. Other direction is not typically over equalized in this case but it is possible.

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TUSB217-Q1: Meaning of "Pre-Channel"