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TM4C129ENCPDT + RJ-45 (with built-in transformer) ESD Protection

Vladim-ir
Prodigy 240 points
Other Parts Discussed in Thread: TM4C129ENCPDT, TPD4E1B06, TPD4E1U06

Hello, everyone!

Please, advice, how to make ESD protection for TM4C129ENCPDT + RJ-45 connector with built-in transformer. There is only case when mcu is used with separated RJ-45 and transformer in the SPMA056.

Regarding SPMA056, Ethernet ESD (4.1.6, p.29):

ESD protection for the MDI differential pairs is strongly recommended. One recommended solution is the SLVU2.8-4 TVS Diode Array, shown in Figure 29 as D14. This device is placed on the differential lines between the transformer and the RJ45 connector. The JEDEC SO-8 package is well suited for routing the transmit and receive differential pairs.


A second solution that can be placed on the device side of the transformer between the termination
resistors on the differential pairs and the transformer is TI's TPD4E1B06. This device is not shown in
Figure 29.

What should customer do if he uses RJ45 connector with integrated transformers? Is TPD4E1B06 (between the termination resistors on the differential pairs and RJ45 connector) enough for neccessary level of protection? If no, please advice the best way to implement ESD protection.

  • 0
    TI__Expert 3425 points

    Hello,

    We are currently evaluating various integrated magnetic solutions and I cannot say at the moment if the TPD4E1B06 would also be officially recommended.

    I will get back once I know the results of our evaluation process.

    -David

  • 0 in reply to Stellaris David
    TI__Genius 12190 points

    In the case where the IC has the transformer on IC the only ESD protection that can be used is between the IC and the connector. TI does not have a solution for that location. Following the recommendation outlined in SPMA056, Ethernet ESD (4.1.6, p.29) is the solution.

     

    Regards,

  • 0
    Expert 1830 points

    ESD protection for the Ethernet connection is an interesting topic. I'm putting together the electrical schematic for our new product and had this factor to consider.

    TI recommends ESD protection.

    The TM4C129 Development Kit certainly has ESD protection. However, LM3S9D96 Development Board uses an RJ-45 connector with built in transformer and there is no ESD protection. The LM3S9D96 has the same ESD Absolute Maximum Rating as the TM4C129ENCPDT, so it's not like the LM3S9D96 is more ESD tolerant (at least from a datasheet point of view).

    I'm no expert in this area, but I suspect that the transformer and capacitor combination provide a level of ESD protection that does not exist for say the USB connector which connects directly to the microcontroller.

    For our design, I decided to put ESD protection for the two data lines for the USB connector, but decided to put no ESD protection for Ethernet. This is even though our design uses a separate transformer and therefore ESD protection placement was no problem. I should also add that although we will build several hundred units, they will only be used in-house therefore out risk profile is low.

  • 0
    Expert 1830 points

    Vladim,

    I am also using the TM4C129ENCPDT in my design. Do you have any information about sample and volume availability?
     
    Regards, Vito
  • 0 in reply to Stellaris David
    Prodigy 20 points
    Hi,
    Do you have any solution to use TM4C129 Ethernet connected to a RJ-45 connector with built-in transformer?

    Thanks

    Flavio
  • 0 in reply to Flavio Bianchi99
    TI__Guru**** 244400 points
    Hello Flavio,

    No. The only recommendation is for Transformerless RJ-45 connector. You may still evaluate the solution as long the UNH Compliancy is met.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Prodigy 20 points
    Hi,
    Why I can not use a RJ-45 connector with built-in transformer?  Many products such as Stellaris, Beaglebone, Freescale boards, etc. permit this. Use of a transformerless RJ-45 connector means more components, more cost and more space on the board!

    Can you can clarify this issue?
     
    Thanks!
    Flavio
  • 0 in reply to Flavio Bianchi99
    TI__Guru**** 244400 points
    Hello Flavio

    I never negated the use of a Built in Transformer with RJ-45. The cost of an integrated Transformer with RJ-45 is higher I believe especially on the Launchpad and hence we moved with separated magnetics

    Regards
    Amit
  • 0 in reply to Guy Yater
    TI__Genius 12190 points
    TI has ESD solutions for ethernet that will work between the magnetics and the PHY. My earlier answer was regarding magnetics built-in to the PHY. In this case, where the magnetics are in the connector, TPD4E1B06 will work. Another recomendation is TPD4E1U06 if the signal swing does not go negative, as TPD4E1B06 is designed for.
  • 0 in reply to Guy Yater
    TI__Guru**** 244400 points
    Hello Guy,

    I have gone through the TPD4E1U06. While it mentions Ethernet, all application examples are for USB2.0. I would be glad if an Ethernet connection diagram can be added to it.

    Regards,
    Amit