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TUSB212: TUSB212 PCB Layout Issue

peng wei
Prodigy 130 points
Part Number: TUSB212
Other Parts Discussed in Thread: TUSB216, TUSB214

Tool/software:

Hello TI Teams：

如下是我们USB2.0的走线图，跨了3块PCB，PCB之间用BTB连接器桥接。

由于CPU最大允许插损是14dB，所以从14dB处到USB2.0 CONN，需要用TUSB212中继以提高增益。

如手册建议的“suggest to place the TUSB212 closer to the USB CONN side(1~2 inch)”，则TUSB212的位置超出了CPU要求的14dB的位置。

Q1. 基于上面这种情况，帮忙看看有什么好的办法解决呢？


Q2 如果靠近USB CONN放置一颗TUSB212，在中间路径上再放置一颗TUSB212是否可行？即同一条USB高速线上使用2颗TUSB212。

Thanks！

  • 0
    TI__Mastermind 42860 points

    Hello,

    If possible, I would appreciate it if you could help translate this questions to English so that I can properly understand your issue in this E2E thread. Thank you!

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 130 points

    Hi Ryan：

    Below is our USB2.0 alignment diagram, spanning 3 PCBs, with BTB connectors bridging between the PCBs.

    Since the maximum allowable insertion loss of the CPU is 14dB, it is necessary to use a TUSB212 to relay the gain from the 14dB to the USB2.0 CONN.

    As the manual suggests “suggest to place the TUSB212 closer to the USB CONN side (1~2 inch)”, the position of the TUSB212 exceeds the 14dB position required by the CPU.

    Q1. Based on this situation above, help to see what is the best way to solve it?


    Q2 Is it feasible to place one TUSB212 close to the USB CONN and another TUSB212 in the middle path? That is, using 2pcs TUSB212 on the same USB Hi-Speed cable.

    Thanks！

  • 0 in reply to peng wei
    TI__Mastermind 42860 points

    Hi Peng,

    peng wei said:

    Q1. Based on this situation above, help to see what is the best way to solve it?


    Q2 Is it feasible to place one TUSB212 close to the USB CONN and another TUSB212 in the middle path? That is, using 2pcs TUSB212 on the same USB Hi-Speed cable.

    It's correct that we typically recommend placing our redrivers closer to the USB connector.

    In this case, if you are seeing 14dB of loss on your system before going out the connector, my recommendation would be to place two redrivers on your connection, one in the middle, like at a connector on the base board, and one at the USB connector like you suggested. In that case though, I would recommend switching from the TUSB212 to the TUSB216. We recommend the TUSB216 in systems that may require two USB2 redrivers, as the TUSB216 has improved performance over the TUSB212, including RX sensitivity, which is meant to help account for the loss associated with longer cable lengths.

    As for EQ settings, I would recommend starting at a lower level though. My main concern with placing two redrivers is that if there is too much compensation, or the signal loss is not that high, then the signal can become over-compensated, which will result in false disconnects. This can be accounted for primarily by using lower levels for the TUSB216 EQ and RX_SEN levels, and increasing as needed.

    If even after that there is too much compensation, you may need to remove one of the redrivers, like the one at the USB connector, and just use the one in the middle at a higher setting.

    Please let me know if you have any other questions.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 130 points

    Hi Ryan：

    Thanks for your reply！We also have the following questions to ask.

    Q3. The following figure shows the TUSB214/216 P2P compatible design, please review the current schematic design to see if it is ok, and if there is any special attention to be paid to the layout of the compatible design.

    Q4. Do we need to pay attention to the following Pin11 charging control function of TUSB216?
    (i.e. there is no need to set aside external pull-down), the main use scenario for end customers is to upgrade the system with a USB Disk drive;

    Q5. Does TUSB216 Pin9 and Pin11 need to be configured with an additional Reset chip for Pin5 after power on for the function to take effect? Currently, the design is default to power on and reset itself, without reserving the Reset pin; Is there any reset timing sequence requirement during the use of TUSB216 functions?

    Thanks！

  • 0 in reply to Ryan Kitto
    Prodigy 130 points

    Hi Ryan：

    we additional three more questions:

    Q6. Can the middle redriver be placed on the SMB board near the middle connector? 

    Q7. Why should the redriver be placed close to the middle connector or USB connector? Can it be placed in the middle route line of the board?

    Q8. RX_SEN corresponds to TUSB216 of pin9,  and ”TUSB216 EQ“ corresponds to pin ？

    Thanks!

  • +1 in reply to peng wei
    TI__Mastermind 42860 points

    Hi Peng,

    peng wei said:

    Q3. The following figure shows the TUSB214/216 P2P compatible design, please review the current schematic design to see if it is ok, and if there is any special attention to be paid to the layout of the compatible design.

    Is I2C being used? If so, please ensure the SDA/SCL lines are being correctly pulled-up to Vi2c, such as with a 4.7KOhm resistor.

    Is RSTN being controlled externally? If so, please ensure the TUSB212 is not enabled until VCC is powered and stable, and before any data is sent through the USB2 lines.

    EQ is set to level 2, and DC_BOOST is set to high. We recommend starting at lower levels, such as EQ level 1 and DC_BOOST mid, that way overcompensation is avoided. For the TUSB216, the same would apply, where we recommend EQ level 1 and RX_SEN level mid.

    For DP/DM, please ensure these lines are connected beneath the redriver to ensure the signal is not broken.

    peng wei said:

    Q4. Do we need to pay attention to the following Pin11 charging control function of TUSB216?
    (i.e. there is no need to set aside external pull-down), the main use scenario for end customers is to upgrade the system with a USB Disk drive;

    If BC1.2 is going to be used in the USB2 signal, yes, this pin needs to be set correctly. If enabled, this will set the host device as charging the device connected downstream. If this is not desired, the capacitor would need to be removed.

    If BC1.2 is not going to be used, I.E no BC1.2 handshake/communication, then this pin can be left connected via the capacitor or the capacitor can be removed for the TUSB216. The cap is required for the TUSB212 and the TUSB214.

    peng wei said:

    Q5. Does TUSB216 Pin9 and Pin11 need to be configured with an additional Reset chip for Pin5 after power on for the function to take effect? Currently, the design is default to power on and reset itself, without reserving the Reset pin; Is there any reset timing sequence requirement during the use of TUSB216 functions?

    There is no need to add any additional functionality for the RSTN pin for pin 9 and pin 11. These pins are sampled at reset/start-up, so unless you intend to change these settings while the TUSB216 is powered, there should not need to be any changes to the RSTN pin.

    peng wei said:
    Q6. Can the middle redriver be placed on the SMB board near the middle connector? 

    Are you referring to the CPU board or base board? Ideally, it would be on the base board, but if needed, it can be on the CPU board. However, if on the CPU board, make sure the settings are low enough to where the disconnect threshold of the HS connection will not be exceeded by the signal.

    peng wei said:
    Q7. Why should the redriver be placed close to the middle connector or USB connector? Can it be placed in the middle route line of the board?

    Typically, we recommend placing redrivers closer to the USB connector to ensure that the signal has the best quality as it enters the signal, and that the signal does not potentially enter the SOC at a level which could trigger a disconnect. If you are placing one redriver, we recommend closer to the connector, but as long as the signal does not exceed the disconnect threshold, you can place it in the middle if needed. If there are two redrivers, these should not be placed right next to each other.

    peng wei said:
    Q8. RX_SEN corresponds to TUSB216 of pin9,  and ”TUSB216 EQ“ corresponds to pin ？

    TUSB216 BOOST is the same as the TUSB212 EQ. The TUSB216 BOOST pin incorporates both AC and DC boost with pin 9 covering RX_SEN, while the TUSB212 EQ pin covers only AC boost, and pin 9 covered DC boost.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 130 points

    Hi Ryan：

    Is RSTN being controlled externally? If so, please ensure the TUSB212 is not enabled until VCC is powered and stable, and before any data is sent through the USB2 lines.

    wp reply --> We uderstand that the RSTN timing needs to complete the dereset operation of the RSTN after the VCC power up, and before the USB signal(DM/DP) is sent;

    Are you referring to the CPU board or base board? 

    wp reply --> We currently have 2 USB Drives(TUSB216 ) placed on the Main Board(SMB), 1pcs near the USB CONN and the other in the middle of the PCB traces.

    Thanks!

  • +1 in reply to peng wei
    TI__Mastermind 42860 points

    Hi Peng,

    peng wei said:
    wp reply --> We currently have 2 USB Drives(TUSB216 ) placed on the Main Board(SMB), 1pcs near the USB CONN and the other in the middle of the PCB traces.

    If possible, I would recommend placing on of those redrivers on the base board, that way loss closer to the CPU board can be accounted for. If not possible, then I would recommend placing one redriver closer to the USB connector, and another closer to the BTB connector.

    Thanks,

    Ryan