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TUSB1210 Layout Guidance

Emkay Kim
Prodigy 270 points
Other Parts Discussed in Thread: TUSB1210

Hi.

I have a quite urgent and simple question on a layout of TUSB1210.

Could you please help me to find the best place to SMT TUSB1210 btw. MCU and USB connector?

The length btw. MCU and USB connector is 200mm, and I’m wondering where the optimized place is, to put TUSB1210 in the middle of them.

 In my point of view, the signal interface btw. TUSB1210 and MCU is single-ended TTL level with 60MHz ref Clock, but the other side is diff. 480MHz signal, so TUSB1210 should be put as close to the MCU as possible.

Please give me your idea.

 Thanks.

  • 0
    TI__Guru 60870 points
    Hello Emkay,

    Yes, please place the TUSB1210 as close to the MCU as possible. Routing guidelines for the TUSB1210 are here: www.ti.com/.../swca124.pdf

    Regards,
    JMMN
  • 0 in reply to JMMN
    TI__Prodigy 270 points
    Hi JMMN,
    My customer got board guidance from Altera, Xlins, and SMSC (Microchip), and they all recommended to place TUSB1210 or PHY chip as close to the connector as possible.
    the reason was 480Mbps is the fastest signal, but It doesn't make sense to me.
    but customer is quite worried about the place so I'm double checking now...
    what do you think?
    TUSB1210 needs to be placed close to MCU since TTL level is vulnerable to noise?
    how close? what mm should it be, if they're length btw MCU to connector is 200mm total?
    Thank you very much.
  • 0 in reply to Emkay Kim
    TI__Guru 60870 points
    Hello Emkay,

    The USB signals are designed to be routed over long PCBs and cables, the ULPI interface is not. I would recommend placing the TUSB1210 closer to the MCU than to the connector. Just make sure that the differential pair from the TUSB1210 is to the connector has proper differential impedance and trace length matching.

    Regards,
    JMMN