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  • TI Thinks Resolved

TPD4E02B04-Q1: ESD protection for USB 2.0 signals

Part Number: TPD4E02B04-Q1

We will be using the FTDI FT601 chip to do the interfacing to the USB 3.0 bus. In our previous USB 2.0 design FTDI recommended also PulseGuard ESD Suppressors - PGB1010603 on the USB 2.0 DP/DM signals as well as 10pF Caps to GND. When I asked them about this requirement for this design using the FT601 they claimed that it was NOT necessary as a different PHY is being used. When I looked at the data sheet for the FT601 ESD and Latch-up Specifications :-

Human Body Mode (HBM)  - JEDEC EIA/JESD22- A114-B, Class 2 - ±2kV 

Machine mode (MM) - JEDEC EIA/JESD22- A115-A, Class B - ±200V

Charged Device Mode (CDM) - JEDEC EIA/ JESD22-C101- D, Class-III - ±500V

Latch-up JESD78, Trigger Class-II - ±200mA

In your opinion is this enough ? In the TPD4E02B04-Q1 data sheet they recommend on the USB 2.0 lines to use TPD4E05U06-Q1 ? What do you think ?

If we do use the TPD4E02B04-Q1 is there a reason why we couldn't use the TPD4E02B04-Q1 for the  USB 2.0 lines \ CC lines instead of the  TPD4E05U06-Q1 ?

  • Shmuel-

    Thanks for your detailed information on your system. The FT601, like almost all IC's, integrated some ESD protection but the HBM/CDM specification is designed primarily to protect the IC in the factory and assembly situation, not in the real world. The best ESD standard to simulate real life use cases (IE someone with a large static build up touching the pins accidentally and discharging to them) is IEC61000-4-2, which contains much more inclement energy than the HBM or CDM pulses. IEC61000-4-2 is what TI specifies all of our ESD protection for, and we always recommend that systems have 8kV IEC 61000-4-2 ESD protection on all external pins for a robust system. Most common consumer equipment meets this requirement to limit field returns.

    With that in mind, the TPD4E02B04-Q1 is a great fit for your application. It is a low capacitance part that will offer 4 channels of flow through routing for your USB 3.0 SS lines and can also protect the USB 2.0 lines. The only time you might need to use the TPD4E05U06 (or the single channel equivalent TPD1E05U06) is on the CC lines, where, depending on the application, the signal can go to 5V (such as in Vconn mode) which is above the breakdown voltage of the TPD4E02B04. Both of these parts offer the 8kV IEC61000-4-2 ESD protection, so they will be very robust.

    Hopefully that's helpful, feel free to let me know if you have any follow up questions or clarifications!

    Thanks,
    Alec
  • In reply to Alec Forbes:

    Dear Alec,
    Thank you so much for that great info.

    So If I am going to need TPD4E05U06\ TPD1E05U06 for the CC lines, then I might as well use it for the USB 2.0 lines (I only have 2 of them) as well since I am going to have to stock this part as well ?!
  • In reply to Shmuel Davis:

    Shmuel-

    If you are using USB 3.0, you can actually use the TPD4E05U06 on every line, including the USB 3.0, USB 2.0 and CC/SBU lines. Not that this is for USB 3.0 - if you are using USB 3.1 Gen 2, you will need to use the TPD4E02B04 or the ESD122 on those lines as they are devices with a higher bandwidth to enable the 10Gbps operation.

    Thanks,
    Alec

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