Original question:
LMK04832-SP: Performance Degradation While Unpowered for Fin0
Tool/software:
Hello,
In the datasheet, it specifies the input pin damage level is 5mA RMS when the receiver is powered OFF. I would like to confirm that there is not a cold-sparing issue if a LMK driver is driving another LMK, given the LMK driver is a true LVDS current source (3.5mA – 4mA) since the vast majority of the current will flow through the 100 ohm termination and not into receiver pin.
Thanks!
Robert
Robert,
There will not be a problem while the LVDS input to the unpowered device if the input is AC-coupled, as shown below. This is because a LVDS signal swings around 400mV which meets the requirement mentioned below. For more information, please refer to the 9.3.1 Cold Sparing Considerations section of the data sheet.
If you are not AC-coupling the inputs of the unpowered device please do so by following this circuit:
Best,
Andrea
