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LMH0387 some questions

NAOKI AOYAMA
Guru 11215 points
Other Parts Discussed in Thread: LMH0387

Hello,

Our customer use the LMH0387, have some questions.

A) It is mentioned the LMH0387 equalizer outputs are internally termination 100ohm LVDS outputs.

  Does it need the another termination resistor at the front of the receiving device?

B) Can the customer cut off the internally termination by the resister configuration?

C) Could you tell me the reason why there is the termination at the transmitter side?

    Usually, the termination resister is receiver side.

D) The customer will use the LMH0387 in the INPUT mode.

   Should the customer stop the signal of the SDI and nSDI?

   or 

   Does the LMH0387 ignore the signal of the SDI and nSDI in the INPUT mode?

Best Regards,

Naoki Aoyama

  • 0
    TI__Guru* 93670 points

    Naoki-San,

    Please below note comments related to your questions:

    A). You are correct normally there should be a 100 ohm termination on the receiving device. In many instances, this is integrated into the receiver. You can look at the receiver AC parameters to see if this is integrated.

    B). No. This is integrated within the device.

    C). For high speed interface, differential 100 ohm is very popular and majority of the receivers have termination integrated. In order to provide optimum signal integrity, we need to have integrated 100 ohm termination.  

    D). Please pull TX_EN pin  low( pin number 40). This will disable the cable driver and SDI/nSDI will be ignored. Here is a link to an app note related to this topic:

    Regards,,nasser

  • 0 in reply to Nasser Mohammadi
    Guru 11215 points
    Hello Nasser-san,

    Thank you for your reply.
    I understood all questions.

    Thanks,
    Naoki Aoyama