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I need a little clarification as to whether it's necessary to have an analog ground for the TPS53647 controller with a single point ground vs simply connecting external component returns to the system ground plane.
The data sheet Layout instructions and the eval board appear to have an analog ground layer that is connected to the power ground at a single point through a 0 ohm resistor.
However, the layout for the 3-phase PMP10962 reference design has some controller components tied to a single point while others tie directly to the ground plane on the top layer. Device thermal pad appears to connect to ground plane on several layers including the top (controller mounted on bottom layer of PMP10962).
Hi Mark,
Separating AGND and PGND is not required. However, the GND plane underneath the controller should be a quiet area. A quiet area is defined as an area where no power supply switching current is likely to flow. 12Vin copper plane underneath the controller should be avoided and keep>60mil clearance.
Thanks,
Nancy
Hi Nancy,
Thanks for the quick reply. One question - if there is a ground plane between the top layer with the controller and the 12Vin copper plane, is this enough isolation, or should the 12V plane still be cleared under the controller?