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SN65MLVD047: SN65MLVD047PW-Load current and Ground current

Srikanth Kacchu
Prodigy 110 points
Part Number: SN65MLVD047
Other Parts Discussed in Thread: SN65LVDT388A, , DS90LV047A, SN65LVDS391

What is the load current and ground current for SN65MLVD047PW M-LVDS QUAD line driver?

  • 0
    TI__Genius 10250 points
    Hello Srikanth,

    Can you please explain what you mean by load and ground currents?

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    TI__Genius 10250 points
    Hello Srikanth,

    Haven't heard back from you for a while. Do you still need support? I will close this thread for now, but you can reply to it and it will get open again.

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    Prodigy 110 points

    Hello Yaser

    I will get back to you soon.

    Srikanth

  • 0 in reply to Srikanth Kacchu
    TI__Genius 10250 points
    Hello Srikanth,

    I haven't heard back from you for a while. I will close this thread for now, but if you still need support please respond and it will get open again.

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    Prodigy 110 points

    Dear Yaser

    We are planning to loopback SN65MLVD047PW driver to SN65LVDT388ADBT receiver with 100 Ohm termination. Does the interface work?

    Else, please suggest me loopback circuit with the same components.

    Regards

    Srikanth Kacchu

  • 0 in reply to Srikanth Kacchu
    TI__Genius 10250 points
    Hello Srikanth,

    What you mean by "loopback" here... Please provide a block diagram or a simple sketch of what you are doing to clarify.
    Are you simply connecting the outputs of SN65MLVD047 to the inputs of SN65LVDT388A? If that's the case, then you should add additional 100 ohm terminations at the output of SN65MLVD047 since it is an M-LVDS driver and expects a load of 50 ohm, not 100 ohm.

    Any reason for selecting SN65MLVD047 M-LVDS driver and not a regular LVDS driver such as DS90LV047A?

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    Prodigy 110 points

    Dear Yaser

    You are correct. I am connecting output of SN65MLVD047 to SN65LVDT388A with external 100 Ohm termination. Since SN65LVDT388A having internal 100 ohm termination. Together makes 50 ohm termination at the output of SN65MLVD047.

    Reason for selecting SN65MLVD047 M-LVDS driver is to driver 4 receivers. I am not sure about  a normal driver can able to load 4 receivers.

    Regards

    Srikanth Kacchu

  • 0 in reply to Srikanth Kacchu
    TI__Genius 10250 points
    Hello Srikanth,

    Just to be clear on the topology, do you have each driver output of the SN65MLVD047 connected to 4 receiver inputs of SN65LVDT388A? These details are important and a diagram or a sketch would be very helpful to make sure we are on the same page.

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    Prodigy 110 points

    Dear Yaser

    While interfacing one board with another board,  each output of SN65MLVD047of one board  will drive 4 receiver inputs in another board. This is one point.

    Next point is, I have SN65MLVD047 driver and SN65LVDT388A receiver in my board. To validate these devices I planned to connect one driver output to one receiver input only. The same circuit is drawn and attached here. I have external termination of 100 ohm at driver output and the receiver has 100 ohm internal termination. Together making 50 ohm at M-LVDS driver output as recommended. So, please check and clarify.

    Regards

    Srikanth KacchuLVDS Loopback.pdf

  • 0 in reply to Srikanth Kacchu
    TI__Genius 10250 points
    Hello Srikanth,

    Thanks for the clarification. The arrangement you described should work fine.
    When connecting to the other board, you need to be careful with the termination scheme to make sure there is a 100 Ohm termination at the output of the SN65MLVD047 and only one termination on the other board at the farthest of the 4 receivers. This means you can't use receivers with integrated terminations.

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    Prodigy 110 points
    Dear Yaser

    Thanks for your clarification and support.

    Yeah, I implemented only one 50 ohm termination resistor at the farthest receiver but not implemented anything at MLVDS driver output.

    Regards
    Srikanth Kacchu
  • 0 in reply to Srikanth Kacchu
    TI__Genius 10250 points
    Hello Srikanth,

    If the media connecting the driver to the receiver is 100 Ohm (as it should be) then 50 ohm at the receiver can generate reflections. It is best to have 100 ohm at the driver and 100 ohm at the receiver.

    Regards,
    Yaser
  • 0 in reply to Yaser Ibrahim
    Prodigy 110 points
    Dear Yaser

    When we drive SN65LVDT388ADBT with SN65LVDS391PW, the max load current is ~16mA and, when driven with SN65MLVD047PW the max load current is ~30mA. Does it overload / damage on receiver?

    Regards
    Srikanth Kacchu
  • 0 in reply to Srikanth Kacchu
    TI__Genius 10250 points
    Hi Srikanth,

    I am not sure about the specific current values you mentioned in your post, but it is true that SN65MLVD047 has a higher current drive than SN65LVDS391, since the former is M-LVDS device and the later is LVDS device. SN65LVDS391 delivers ~3.5 mA typical, while SN65MLVD047 delivers ~ 11.3 mA typical.
    In any case this will not "overload" the receiver.

    Regards,
    Yaser