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SN65LVDS93: Overshoot rating

Sina Vosooghi
Prodigy 60 points
Part Number: SN65LVDS93

I am using the SN65LVDS93 in my design and I see about 1V of +/-overshoot on the parallel Dx input pins. I can't find any overshoot ratings on the datasheet. What are the +-Overshoot ratings for the input pins of this device. Our PCB is very tight and I would rather not add any source termination resistors if I don't have to. 

Cheers

Sina 

  • 0
    TI__Intellectual 2915 points
    Hi,

    You can't exceed the absolute maximum rating on page 4 of datasheet. What are your IOVDD and the maximum input voltage at the Dxx input pins? Any reason why large overshoot/undershoot are at the input TTL?

    What is your end application? We have newer devices you can choose for your design.

    Dennis
  • 0 in reply to Dennis Wu
    Prodigy 60 points
    Hi Dennis,

    IOVDD is 3.3V and the spike at DXX input is 4.2V and -1V for the undershoot. The device is connected to the AM57x VOUT parallel bus. The over/undershoot is caused by the capacitance of the load and the inductance of the traces which is common. This is usually solved by adjusting the drive strength of the output buffer. AM57 supports adjustable strength for some interfaces such as DDR and MMC but not the parallel VOUT. Therefore my only solution is to add damping resistors. I was hoping to get an accurate overshoot/undershoot rating for this part since the spikes only last about 2ns and usually don't fall under the absolute maximum rating since they are very short lived.
  • 0 in reply to Sina Vosooghi
    TI__Genius 10250 points
    Hi,

    Your best bet is to include the damping resistors, as you mentioned, otherwise there can't be a gurantee things will work out for any device and under all conditions.

    Regards,
    Yaser