Buck Converter

Steps a higher DC input (9–18 V) down to a steady 5 V at up to 3 A, efficiently. Unlike a linear regulator (which burns the extra voltage as heat), a buck switches the input through an inductor, so ~85 % of the input power reaches the load.

• U1 — the switching controller. Compares the feedback voltage to an internal reference and switches SW to hold the output at 5 V.
• L1 — the inductor, storing and releasing energy each cycle. This is the mechanism that makes a buck efficient.
• Cin / Cout — input bulk + output smoothing/stability.
• R1 / R2 — the feedback divider. The ratio sets the output voltage: Vout = Vref × (1 + R1/R2) → 0.8 V × (1 + 39k/10k) ≈ 5 V.

Exposes: vin (9–18 V), vout (+5 V, 3 A), and grounds.

⚠ Cin is rated 25 V — keep the input below ~20 V or it's the first thing to let go.