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Once the schematic diagram is complete, the next step is to convert it into the type of data needed to start a circuit board design. This process of “packaging” a schematic creates a part list and a net list.
Let’s imagine that our schematic features two identical circuits, and each one of these circuits contains a pair of op-amp symbols, for a total of four op-amps. We need to assign these op-amps to a specific component type, and we have found two different components that would be acceptable. One is a “dual” package and the other is a “quad.” Without going into the details of why we would choose one over the other, we need to notice that depending on which one we select, the part list and net list will change. If we use two dual packages, we will have a U1 and a U2 with pins numbered 1-8. If we use a quad package we will only have a U1, but the pins will be numbered 1-14. Both the net list and the part list will be affected by our choice.Read the full column here.Editor's Note: This column originally appeared in the March 2013 issue of The PCBDesign Magazine.