Buck Converter: Understanding Voltage Regulation Through 2D Waveform Analysis

What is a Buck Converter

A buck converter is a type of DC-DC power converter that reduces the voltage from a higher input value to a lower output value. It does this by using an inductor, a switch (often a MOSFET), and a diode to store energy during the on-time and release it during the off-time.

The key components are the inductor, which stores energy as magnetic field, and the capacitor, which smooths out the output voltage.

How It Works

In a buck converter, when the switch is closed (on), current flows through the inductor and charges it. When the switch opens (off), the inductor releases its stored energy through the diode into the load.

The duty cycle of the switch controls how much time the inductor has to store energy, thus determining the output voltage.

Continuous Conduction Mode vs Discontinuous Conduction Mode

In Continuous Conduction Mode (CCM), the current through the inductor remains constant throughout the switching cycle. This occurs when the load is high enough to keep the inductor from reaching zero current before the next switch on period.

Discontinuous Conduction Mode (DCM) happens when the load is low, causing the inductor to reach zero current during each off-time of the switch.

Efficiency and Ripple

The efficiency of a buck converter depends on various factors including the switching losses due to the MOSFET and diode, as well as the ripple voltage across the output capacitor.

Ripple is the variation in the output voltage that occurs due to the charging and discharging of the inductor during each switching cycle.

Frequently asked questions

Try it live

Everything above runs in your browser — open Buck Converter: 2D Waveform Lab and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.