The power stage of the switching power supply generally refers to part of the circuitry where high current flows. It includes an input capacitor, inductor, transformer (for isolated supplies), switch, rectifier, and output capacitor. This part of the circuitry not only has large current flow, but also operates at high switching frequency and generates relatively high interference.
The analog part of the switching power supply is also known as the control loop, which includes the controller chip and the feedback loop. There is no large current flowing through this part of the circuit, and it is susceptible to interference.
Under normal circumstances, the power stage and the control loop of the switching power supply need to be separated during board layout in order to prevent the high frequency interference of the power stage from affecting the operation of control loop. The ground (power ground) of the current path especially needs to be separated from the ground (analog ground) of the control loop, and there should be a single point of contact between them at the ground of the input capacitor.
Since there is no evaluation board for MAX16961, we can use the evaluation board of MAX16962 as the reference for board layout. The layout of the MAX16962 evaluation board is shown in the figure below, where the power path and analog path are marked. We can see that the power components and high-current path are isolated from the analog circuitry.