Explain the operation of a buck converter and its key design equations.

A buck converter steps down voltage using a switch (MOSFET), diode (or synchronous MOSFET), inductor, and capacitor. During switch ON, inductor current rises as energy is stored; during OFF, inductor releases energy through the diode. Key equations: Duty cycle D = Vout/Vin, Inductor L = (Vout*(1-D))/(fs*delta_IL) where delta_IL is ripple current, Output capacitor C = delta_IL/(8*fs*delta_Vout). Continuous conduction mode requires minimum load current. Efficiency can exceed 95% with proper design.