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fault analysis of DS90LV001

anum khan
Prodigy 50 points
Other Parts Discussed in Thread: DS90LV001

I WANT TO PERFORM THE FAULT ANALYSIS OF DS90LV001LVDS BUFFER. I WANT TO KNOW THAT IF THE INPUT PINS OR OUTPUT PINS GET SHORT THEN WHAT LOGIC WOULD APPEAR ON THE OUTPUT PINS. OR WHAT WOULD APPEAR AT THE OUTPUT IF ANY OF THE INPUT PIN GET SHORT WITH THE DC SUPPLY??

  • 0
    TI__Guru**** 181521 points

    Hi Anum,

    I've moved your post to a more appropriate forum.

  • 0 in reply to Tom Hendrick
    Prodigy 50 points

    Thank You Tom

    Regards

    Anum

  • 0
    TI__Expert 5175 points

    Greetings -

    The DS90LV001 is a LVDS Repeater.  The differential input is specified for a High state when the input is >= +100mV, a Low state will be for a signal greater than -100mV.  If you tie the inputs together, that is VID = 0V which is in the middle of the threshold state, outpuy could be HIGH or LOW or in the presence of differential noise even oscilate.  Usually with a LVDS bus, the signal transitions quickly through the threshold region for a clean switch.  If one has a un-drivernbus, external bias restsors are commonly used to set the line to a stable state with a known value (eg +125mV bias) - see application notes on Failsafe biasing. 

    John Goldie

  • 0 in reply to John Goldie
    Prodigy 50 points

    Thank you Mr.Goldie

    I have gone through the application note and thats very helpful.

    In my design the LVDS output of the repeater is connected to two x-band transmitters. one is functional and the other one is redundant. and they work in a switchable manner. during any fault condition in one transmitter the LVDS output will be moved on to the other transmitter. i now want to isolate the inputs of the two transmitters so that if one transmitter is mal functioning then it won't effect the operation of the other. how can i isolate high speed rf links without disturbing the signal integrity of the signal??

    regards

    Anum

  • 0 in reply to anum khan
    TI__Expert 5175 points

    Hi -

    I am not sure I fulley understand the question.  I think you might be asking how to isolate the two drivers.  Due to high speed edges that is tricky.  Some have used a high bandwidth relay to switch between the drivers, but a high quality, impedance controlled relay is needed - they tend to be large and expensive.  If high isolation is needed two seperate links to redundant RECs might be a better approach.  I will be traveling and unable to respond in a timely manner - best wishes on your application.

    John