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TPD2E001 (Rev. E) specification of RT and C plus pad design

GJ Zeilstra
Prodigy 10 points
Other Parts Discussed in Thread: TPD2E001

In the slls684e.pdf is the specification/datasheet for the TPD2E001. It also specifies the recommended parts RT and C. Unfurtunately it does not give all required values for these parts not parts that are recommended as starting point. Are the following parts correct? Or is there a better part that we should be using:

RT, we image something like 1, 27 or 100 Ohms but don't know this for sure, SMD style. We are not sure what the value is and if there are additional requirements with respect to wattage for example.

C, at 0.1 micro F, probably should be rated at 200 V (100+VCC plus some arbitrary margin with minimum of 125V), ceramic. Mutlicomp MCCA000819 may be a good part. ???

The guide is straight forward but does not hint to design guides besides the DZD pad sizes. It would be nice to see what is the best layout because this is a critical element for us. Placing of RT and C and relative to connector and ground plane may be very important elements but there is not detail in the PDF on this. We are using EAGLE 6 and made a first draft part but know that this may not be enough.

  • 0
    TI__Intellectual 2520 points

    Zeilstra, I am looking into this and should have a response to you by tomorrow the latest.

    Vivek

  • 0
    TI__Intellectual 2520 points

    GJ,

    1. The Rev F has been uploaded online for future use.

    2. The RT value is based on your system. If this is a Full Speed USB, then you'd require a typical termination of 20-44 ohm. This includes your input impedance + your output impedance + any trace resistance + RT. Typically based on your speed on the signal you can pick values like 10 ohm and if you have to go faster you could use 1 ohm or even short it out with a 0 ohm. Its hard for me to suggest the accurate value without knowing the system.

    3. C value: it need not be rated at 200 VCC. it can be as low as 10V. VBUS is usually 5V and then you add some buffer.

    4. Layout guidelines: I have noted your suggestion and will include it in future versions of the guide. If needed we'd be glad to look over a section of your gerbers to determine if the layout is suitable.

    Thanks
    Vivek