Forum Discussion
New ContributorInvestigation of HIGH-Level Voltage Fluctuations on MAX 10 3.3 V LVTTL Output Signals
Super ContributorHi,
some additional questions:
Are you seeing level variations in static voltage (DC or slow signal) or in high level of a pulse waveform (MHz speed)?
In the latter case, are you sure that it's no measurement artifact, e.g. due to unsuitable probing?
You say external device is DS90CR287, presume you are feeding CMOS inputs without additional load?
Regards Frank
y-fujiwara1. The issue is a variation in the high-level voltage of a pulse signal in the 1 MHz range.
2. An active probe is used, with the GND connection made through the shortest possible via.
3. No additional load is applied.
We also confirmed with TI that noise from the LVDS signal may couple through the IC's internal circuitry.
Since this phenomenon has not been observed on signals connected to other devices, we believe this is the likely cause.
