11.1 Layout Guidelines

For best accuracy and minimum noise, the printed circuit board containing the DAC128S085 should have separate analog and digital areas. The areas are defined by the locations of the analog and digital power planes. Both of these planes should be located in the same board layer. A single ground plane is preferred if digital return current does not flow through the analog ground area. Frequently a single ground plane design will utilize a "fencing" technique to prevent the mixing of analog and digital ground current. Separate ground planes should only be utilized when the fencing technique is inadequate. The separate ground planes must be connected in one place, preferably near the DAC128S085. Ensure that digital signals with fast edge rates do not pass over split ground planes. The signals must always have a continuous return path below their traces.

11.2 Layout Example

Figure 34. Layout Example