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LMH1297: Register setting

Masazumi Ishii
Genius 3945 points
Part Number: LMH1297
Other Parts Discussed in Thread: SIGCONARCHITECT, LMH0397

hello.

We will create a board and start the evaluation.

At this time, what is the recommended register setting value when measuring return loss?
please tell me.

the reason
In case of no signal, it is because there is a possibility that the termination may have run out because it enters automatic power down mode.

Thank you.

  • 0
    TI__Guru* 93670 points
    Hi Ishii-San,

    For LMH1297, suggestion is to setup the device in Equalizer mode (EQ/CD_SEL pin 5 low). To measure return loss in EQ mode, no special setting is required. After pulling pin 5 low, you can power the device and do return loss measurement.

    Normally return loss measurement in cable driver mode is better than equalizer mode. To measure return loss in cable driver mode, there should signal present on IN0 of LMH1297 and then we should enable 10-MHz clock on 75-ohm outputs. Your customer can use SigconArchitect GUI to setup the device in this mode. Alternatively, your customer can read LMH1297 programming guide and setup device registers to transmit this 10-MHz clock.

    Regards,,nasser
  • 0 in reply to Nasser Mohammadi
    Genius 3945 points

    Hello.

    Thank you for your reply.

     I have an additional question.

    We will use the LMH1297 and LMH0397 in EQ mode.

    How should we set when measuring the return loss of SDI_OUT (loop-through)?

    Thank you.

     

  • 0 in reply to Masazumi Ishii
    TI__Guru* 93670 points

    Greetings Ishii-San,

    You can enable 10-MHz clock on SDI_OUT either through AigconArchitect GUI or through register settings. Please note attached graph. Also, please refer to the LMH1297/LMH0397 programming guide.

    Regards,,Nasser