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ONET1130EP: Squelch behaviour on ONET1130EP TxOut

Gilles Froidevaux
Prodigy 20 points
Part Number: ONET1130EP

Hi,

We are an electronics development company and we are developing a product for a client to convert electrical signals into optical signals at a frequency of 5Gbps.

The signals to be transmitted are a personalized signal with a squelch state which lasts between 5us and 1ms. How do the "TxOut" outputs of the ONET1130EP chip behave when the "TxIn" signals are squelched (V (TxIn +) = V (TxIn-)) ? Is the output undefined or the ONET1130EP can also squelch the signals if the voltage difference of the TxIn inputs is less than a certain threshold?

Thank you in advance for your answer.

  • 0
    TI__Guru* 93670 points

    Greetings,

    Based on the AC coupling cap on TXIN, there could be two cases:

    1). There could be chattering on the input such that it would not cause TX fault - if enabled - and this may cause the driver to modulate the laser randomly.

    2). There is indeed a constant high or constant low. This may cause TX fault - if enabled.

    If TX fault is disabled and we are AC coupled to the laser then this depends on the laser being modulated.

    Regards,, Nasser

  • 0 in reply to Nasser Mohammadi
    Prodigy 20 points

    Thank you for your reply.

    If I understood correctly when reading the datasheet, the TX fault is not instantaneous and can take up to 50us before being activated.

    Therefore, during this time (before TX fault is asserted) the driver modulates the laser randomly, even if TXIN is squelch.

    Is it correct ?

    Regards

    François

  • 0 in reply to Gilles Froidevaux
    TI__Guru* 93670 points

    Greetings Francois,

    Our option is to use TX_DIS which is typically 1uS - max 5uS. However, i am not sure if you have a way or mean to enable TX_DIS during data transmission.

    Regards,, nasser