Issue link: https://resources.pcb.cadence.com/i/1532922
And here is how the design holds up to that constraint: The actual count is green, meaning we are within our 4-via limit. The margin is 1, so we can add one via and still be within the limit. Characteristic impedance Specify target impedance values (e.g., 50Ω for single-ended traces, 100Ω for differential pairs) to minimize reflections and ensure compatibility with specific communication protocols. This involves controlling trace width, spacing, and dielectric properties. Our manufacturer said they can do 50 Ohm single ended impedance on traces but within a 10% tolerance without charging significantly more money. So, we'll go with that option below. Note: The differential impedance can be calculated from the Cross Section Editor for the PCB Stackup. It is found in the OrCAD X Presto PCB Editor menu item Tools – Cross Section. How to use the tool to do the calculations is outside the scope of this guide. For now, assume that a 50-ohm single-line impedance is roughly an 85 to 130 Ohm differential impedance. But use the calculated values for differential impedance from the Cross Section tool, then input those values into the Differential Pair part of the Constraint Set. The single-ended impedance range could end up being violated for differential traces, depending on the situation, and still be okay for the design to perform. TIP: For Tolerance, you can simply type a value, then the software will assume you mean Ohms. For example, type in 10, then hit Enter. Your software will set it to 10 Ohm. You can type in 10 % instead, however, and it will adjust the Ohm accordingly without you having to calculate it. The PCB designer routed the traces and they fall outside the single ended impedance range, but that's fine. For traces that need single-ended to be 50 Ohms, it works out fine. 49 www.cadence.com OrCAD X Constraint Management Guide