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SN65MLVD203: Is there failsafe circuit in the Receiver Input ?

Shinichi Inoue
Guru 22446 points

Part Number: SN65MLVD203
Other Parts Discussed in Thread: SN65MLVD207

Tool/software:

Dear Specialists,

My customer is considering SN65MLVD203 and has questions.

I would be grateful if you could advise.

---

Regarding SN65MLVD203

(1) Is there failsafe circuit in the Receiver Input? 

(2) LVDS receiver(not MLVDS receiver) has generally has a offset voltage by failsafe circuit, how about SN65MLVD203?

(3) If question (1) and (2) is Yes,  when the input pin is shorted, the output should be either H or L depending on the logic before the short and the individual part, is this understanding correct?

I assumed the following,

If, like the LVDS receiver (DS90LV047), there is a built-in fail-safe that is offset 10m to 30mV to the negative side,
I interpreted that the 25mV hysteresis (L → H) would transition near VID = 0V.

(4) Could you please provide the application note of failsafe bias circuit regarding MLVDS receiver. 

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I appreciate your great help in advance.

Best regards,

Shinichi

  • +1
    Guru 324950 points

    The SN65MLVD203 is a type-1 receiver and does not hafe fail-safe thresholds; see the explanation on p. 18.

    Use the SN65MLVD207 instead.

  • 0 in reply to Clemens Ladisch
    Guru 22446 points

    Hi Clemens,

    Thank you for your reply.

    I understand.

    The datasheet says there is no failsafe circuit.

    I'll share this information with the customer and make them consider SN65MLVD207.

    When the customer has an additional question, I consult you again.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    Guru 22446 points

    Hi Clemens,

    The customer has an additional question.

    Could you please advise?

    ---

    The SN65MLVD203 does not have a built-in fail-safe,  is it possible to leave the input pin floating when not in use?

    When /RE is H or open, the output becomes High-Z.
    Is the receiver circuit stopped at that time?

    If the SN65MLVD203 receiver circuit is operating, there is no fail-safe, so I am worried that if the input is open, internal circuit output H/L, just before the output due to noise.

    ---

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • +1 in reply to Shinichi Inoue
    TI__Guru* 80711 points

    Hi Shinichi,

    Shinichi Inoue said:
    The SN65MLVD203 does not have a built-in fail-safe,  is it possible to leave the input pin floating when not in use?

    If you disable the receiver circuit than this is okay to do.

    Shinichi Inoue said:
    When /RE is H or open, the output becomes High-Z.
    Is the receiver circuit stopped at that time?

    Yes, the receiver circuit is technically disabled during /RE pulled high. 

    If the customer is concerned about the floating input pins A and B they can add external resistors (a pull up on A and a pull down on B) to apply a known bias to the input. 

    -Bobby

  • 0 in reply to BOBBY
    Guru 22446 points

    Hi Bobby,

    Thank you for your reply.

    The customer understood your answer.

    The receiver inputs are used floating.  .

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi