Basic Calculation of Buck Converter

Buck Inductor Formula:

\[ L = \frac{(V_{in} - V_{out}) \times D}{\Delta I \times f} \]

Input Voltage (V_in):

Output Voltage (V_out):

Duty Cycle (D):

(0-1)

Current Ripple (ΔI):

Switching Frequency (f):

Inductor Value (L):

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1. What is Buck Converter Inductor Calculation?

The buck converter inductor calculation determines the appropriate inductance value for a buck (step-down) converter circuit. This value ensures proper current ripple and efficient power conversion in the switching regulator.

2. How Does the Calculator Work?

The calculator uses the buck inductor formula:

\[ L = \frac{(V_{in} - V_{out}) \times D}{\Delta I \times f} \]

Where:

\( L \) — Inductance in Henrys (H)
\( V_{in} \) — Input voltage (V)
\( V_{out} \) — Output voltage (V)
\( D \) — Duty cycle (0-1)
\( \Delta I \) — Current ripple (A)
\( f \) — Switching frequency (Hz)

Explanation: The equation calculates the inductance needed to maintain the desired current ripple at the given switching frequency and voltage conversion ratio.

3. Importance of Inductor Calculation

Details: Proper inductor selection is critical for buck converter efficiency, output voltage ripple, and transient response. An incorrectly sized inductor can lead to excessive losses or instability.

4. Using the Calculator

Tips: Enter input and output voltages in volts, duty cycle (0-1), desired current ripple in amps, and switching frequency in Hz. Typical current ripple is 20-40% of output current.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical current ripple value?
A: Usually 20-40% of the output current. Higher values allow smaller inductors but increase output ripple.

Q2: How does switching frequency affect the design?
A: Higher frequencies allow smaller inductors but increase switching losses. Typical frequencies range from 100kHz to 2MHz.

Q3: What if my calculated inductor isn't available?
A: Choose the next higher standard value. Ensure it can handle the peak current without saturating.

Q4: How does duty cycle affect the calculation?
A: Maximum inductor current ripple occurs at D = 0.5 (when Vout = 0.5 × Vin).

Q5: What about inductor current rating?
A: The inductor must handle the peak current (average current + ½ ripple current) without saturating.