Part Number: LMZ31710
Hi,
In the datasheet of LMZ31710, it is told not to connect AGND (analog ground) with PGND (common ground) because they are connected internal to the IC.
[1] What are the reasons for recommending not to connect AGND in PGND?
[2] Why are Radj and Rrt_clk referenced to ANGD and not to PGND?
I normally maintain one solid ground plane on layer 2 instead of dividing the ground planes. If I follow the recommended layout, I need to divide this solid ground plane. Having different grounds in a circuit board has its own set of problems; so I don't prefer to go to that path.
In the Zynq 7000 SoC EVM (zc-706; reference device - U98), AGND is routed as thick trace in layer 1, while underneath it in layer 2 is a solid PGND ground plane. In such a case, the EM fields of any signal in between Vadj - AGND connection and RT_CLK - AGND connection are contained within the traces on layer 1 and PGND ground below. This means that the PGND ground is referenced anyhow.
[3] Do you think the way it is routed in Zynq SoC okay?
[4] I have the exact same question for the routing of Radj between Vadj and AGND in the new power module TPSM84A22.
Thanks,
Binayak