Proper PCB design and layout is important in a high-current, fast-switching circuit (with high current and voltage slew rates) to achieve a robust and reliable design. As expected, certain issues must be considered before designing a PCB layout using the LM25149. The high-frequency power loop of a buck regulator power stage is denoted by loop 1 in the shaded area of Figure 11-1. The topological architecture of a buck regulator means that particularly high di/dt current flows in the components of loop 1, and it becomes mandatory to reduce the parasitic inductance of this loop by minimizing its effective loop area. Also important are the gate drive loops of the high-side and low-side MOSFETs, denoted by 2 and 3, respectively, in Figure 11-1.

Figure 11-1 DC/DC Regulator Ground System With Power Stage and Gate Drive Circuit Switching Loops