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Other Parts Discussed in Thread: SN65LVPE502, SN65LVPE502CP

a) It is my understanding that the SN65LVPE502CP actually supports the CM Mode functionality of the earlier SN65LVPE502 part, even though the datasheet labels the CM pin (Pin 14) as RSVD.  Please confirm that this is the case.

b) Does the SN65LVPE502CP respond to changes in the CM pin while the EN_RXD pin is high (enabled), or is it expected/required that the CM pin remain static before and/or during and/or after EN_RXD is asserted and later deasserted?

c) If the SN65LVPE502CP expects/requires the CM pin to be stable from some time before EN_RXD is asserted, while EN_RXD is asserted, and through some time after EN_RXD is deasserted, what setup and hold times for CM are required relative to the rising (assertion) and falling( deassertion) edges of EN_RXD?

  • Hello,

    You should leave CM unconnected.

    When the polling times out the device will automatically enter in compliance mode.

    What is your implementation that requires to force the device into compliance mode?


  • 1) I appreciate your recommendation that the TI IC's CM pin be left unconnected and thus default per its internal pulldown to a low level, however I'd appreciate even more some direct answers to my three as-posted questions, above :)

    2) The questions relate to what functionality the TI buffer IC exhibits relative to its CM pin, and do not involve in any way what functionality a USB3.0 device would be expected to exhibit or not exhibit per the USB3.0 Specification's "Compliance Mode" USB device state.

  • Hello,

    Answering your first questions:

    a) Yes, this is tru.

    b) The 502CP will respond to CM pin changes while EN_RXD is high.

    c) N/A, see above.

    Please also note that we recommend to use the LVPS502A or LVPE502B as those fix the Erratas on the LVPE502CP.


  • Thanks for your response.

    Part of the reason the LVPE502CP is being used is because it was designed in before the later parts were available, and it is not clear beyond the errata fixes whether other possible changes in functionality (or pinout) might have also been made which might compromise the needed functionality, which includes the ability to put the part into CM when desired, and to be able to have no deemphasis on the output signals when required.