Inductor Value for Buck Regulator (DCM) Calculator

Critical Inductance Formula:

\[ L_{x(bu\_dcm)} = \frac{t_{c(bu\_dcm)} \times D_{bu\_dcm}^2 \times V_{i(bu\_dcm)} \times (V_{i(bu\_dcm)} - V_{o(bu\_dcm)})}{2 \times i_{o(bu\_dcm)} \times V_{o(bu\_dcm)}} \]

Time Commutation of Buck DCM:

Second

Duty Cycle of Buck DCM:

(0 to 1)

Input Voltage of Buck DCM:

Volt

Output Voltage of Buck DCM:

Volt

Output Current of Buck DCM:

Ampere

Critical Inductance of Buck DCM:

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1. What is Critical Inductance in Buck DCM?

Critical Inductance of Buck DCM refers to the minimum value of the inductance required in these converters to maintain current flow through the inductor in Discontinuous Conduction Mode (DCM). It ensures proper operation and stability of the buck regulator circuit.

2. How Does the Calculator Work?

The calculator uses the Critical Inductance formula:

\[ L_{x(bu\_dcm)} = \frac{t_{c(bu\_dcm)} \times D_{bu\_dcm}^2 \times V_{i(bu\_dcm)} \times (V_{i(bu\_dcm)} - V_{o(bu\_dcm)})}{2 \times i_{o(bu\_dcm)} \times V_{o(bu\_dcm)}} \]

Where:

\( t_{c(bu\_dcm)} \) — Time Commutation of Buck DCM (seconds)
\( D_{bu\_dcm} \) — Duty Cycle of Buck DCM (0 to 1)
\( V_{i(bu\_dcm)} \) — Input Voltage of Buck DCM (Volts)
\( V_{o(bu\_dcm)} \) — Output Voltage of Buck DCM (Volts)
\( i_{o(bu\_dcm)} \) — Output Current of Buck DCM (Amperes)

Explanation: The formula calculates the minimum inductance required to maintain discontinuous conduction mode operation in buck regulators, ensuring proper current flow and circuit stability.

3. Importance of Critical Inductance Calculation

Details: Accurate critical inductance calculation is crucial for designing efficient buck regulator circuits, ensuring proper operation in DCM mode, preventing current discontinuities, and maintaining stable output voltage regulation.

4. Using the Calculator

Tips: Enter time commutation in seconds, duty cycle (0 to 1), input and output voltages in volts, and output current in amperes. All values must be positive and valid for proper calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is Discontinuous Conduction Mode (DCM)?
A: DCM is an operating mode where the inductor current falls to zero during each switching cycle, unlike Continuous Conduction Mode (CCM) where current never reaches zero.

Q2: Why is critical inductance important in buck regulators?
A: Critical inductance ensures the converter operates in the desired conduction mode, affects efficiency, output ripple, and overall circuit stability.

Q3: How does duty cycle affect critical inductance?
A: Critical inductance is proportional to the square of the duty cycle, making it highly sensitive to duty cycle variations.

Q4: What happens if inductance is below critical value?
A: The converter may enter unexpected operating modes, experience increased current ripple, reduced efficiency, and potential instability.

Q5: Can this formula be used for other converter topologies?
A: This specific formula is designed for buck converters operating in DCM. Other topologies (boost, buck-boost) have different critical inductance formulas.