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DS90UB954-Q1: Add ESD protection on the Link

Part Number: DS90UB954-Q1
Other Parts Discussed in Thread: TVS1400, TPD1E01B04, TPD1E05U06-Q1, ESD122

Dear *,

we want to add ESD protection on the FPDLINK III. Please can you confirm the right placement for protection?


a) Place the Power ESD diode after the ferite beads and inductor, so that the capacitance don't affect the forward channel speed ?

b) Is the TVS1400 better choice than PTVS12VS1UR , and why?


a) Place the Signal ESD diode between AC cap and the RIN+ pin?

b) Do we also need ESD diode on RIN-  between AC cap and the RIN- pin

c) Which i better choice TPD1E05U06-Q1 or TPD1E01B04, or maybe 2 channel ESD122?


Regarding the AC capacitor:

a) is there a big impact on signal integrity if choosing 0603 footprint over 0402 or 0201 ? ( in DS 0402 recommended 50V)

b) is it better to chose a higher rated cap eg. 100V regarding ESD protection?

Best Regards,


  • 1. This is ok.

    2. Our recommendation is to place the ESD diode close to connector instead of between AC cap and RIN pins.


    0603 footprint should be ok. On 954 datasheet we talks about this in section 10.1 paragraph 3.

    100V rated caps wont hurt; however, if you place the ESD diode close to connector, the voltage should already be clamped before reaching ac cap. 

    Please let me know if this address some of your questions. For comparison between ESD diode, I would have to reroute the questions to different teams.

    Best Regards,

    Charley Cai

  • Dear Charley,

    1) Please could you comment what type of diode is suitable here?

    2) a) Please can you tell what diode type/part-number do you suggest to place between AC cap and connector?

    b) in this thread ""

    TPDxE05U06-Q1 was suggested but the working voltage of this diode is 5V , and at our FPD Link we have 12V working voltage

    3)is there any positive or negative effect if TPDxE05U06-Q1 placed between AC cap and RIN pin?

    Best Regards,


  • Hello,

    The TVS1400 cannot be used in FPD link because it has slew rate limitations. however if this is just for the power source then it can be used and the advantages of the Flat Clamp devices are outlined in the technical documentation tab of the product folder.

    ESD122 can work and comes in a very small package for space savings

  • Dear Cameron,


    so you suggest to use ESD122 on RIN+ and RIN- pins?

    The diode must be placed between RIN pins and AC caps and not between connector and AC caps is this correct?

    2) is there a diode ESD diode that can be placed between input connector and AC caps when the PoC voltage of FPDLink is 12V?

    Best Regards,


  • David,

    ESD122 would have to be after the AC caps as the working voltage is 3.6V

    It depends on what will be seen on the connector side. Are you just protecting from ESD or surge as well?

    Also what is the signal speed? The capacitance of the ESD diode has to be low enough to support it. Typically I have heard FPDlink III speeds are ~3GHz that would mean we do not have a 12V ESD solution that can be used to protect it.

  • Dear Cameron,

    we would like to protect against IEC 61000-4-2, IEC 61000-4-4 and if possible IEC 61000-4-5

    From FPDLink if i'm not wrong the data rate is 4.16Gbps and the frequency is 2.1GHz. And we are using 12V to have lower current through cable.

    The question is does it make sense to put the EST diode ESD122 or TPDxE05U06-Q1 after the AC capacitors ?

    I understand that this ESD122 is no god between connector and AC caps because it will not work with 12V, also the TVS1400 is not good between connector and AC caps because it is not designed for high speed. 

    So we see two possibilities to protect the port:

    a)  have a high speed ESD diode that works with 12V to put it between connector and AC caps

    b) to put slow ESD diode after the ferrite beads that will cover 12V for power AND put a high speed ESD diode after the AC caps for protecting the RIN+ ( we don't know if we need to protect RIN-)

    So the question is , is there a ESD diode that can be put between connector and AC caps, and if no does it make sense to implement solution b) ?

    Best Regards,


  • Hello,

    We do not have ESD devices that can protect in this scenario between the connector and AC caps.

    You could do it in that way and we have our TVS diodes such as TVS1400 that would protect the DC power and then have the small ESD diodes that can be after the capacitors.