The design uses buck topology to generate 3.3V output using LM2671 buck controller operating at 260kHz. This is a simple switcher which requires a minimum number of external components and includes internal frequency compensation. Operating at 260kHz allows the design to use smaller size filter components.PC board layout is critical in achieving low switching losses and clean, stable operation. The switching power stage requires particular attention. Few points to note for this design are:
1) Decoupling capacitors are as close to IC pins as possible. Keep separate power ground plane.
2) Input and output capacitors are connected to the power ground plane; all other capacitors are connected to the signal ground plane.
3) Feedback connections are short, direct, and routed away from any noisy traces (i.e. switch node).
Schematic
Example Schematic Showing Connection for all Components.
Example Schematic Showing Connection for all Components.
