Hi TI experts,
In some situations, it is required to separate Analog and Digital ground when using mixed signals. Based on what is written in the AM3871 specification, I see that this is not required.
1. I want to understand why this requirement does not apply to this processor? Explain, please.
I mean a similar scenario:
2. I noticed that the DDR_VREF pins, as well as some USB-bus pins, such as USB0_DP, USB0_DM and others, have an analog signal type (A). Why is it that way?
3. I cannot understand why a digital interface such as USB is marked in the documentation as an analog signal type (A)? Explain, please.
4. Does this mean that they require the presence of an analog ground plane under the tracks for return currents where these signals pass?
5. Is a solid reference plane needed for the power polygons on the inner layers? Does the gap in the plane on the adjacent inner layers if it intersects the polygon for example analog power on the adjacent inner layer?