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Buck Converter Calculator
This calculator estimates key design values for a buck converter, including duty cycle, inductor ripple current, recommended inductance, output capacitor ripple, input current, and output power. It is useful for switching regulator design, DC-DC converters, power supplies, embedded systems, and battery-powered electronics.
Input Parameters
Results
These values are first-pass estimates. Final component selection should include regulator datasheet limits, saturation current, RMS current, ESR, layout, thermal margin, and transient response.
Equations Used
Duty Cycle:
D = Vout / Vin
Inductor Ripple Current:
ΔIL = Iout × Ripple Percentage
Recommended Inductance:
L = Vout × (Vin - Vout) / (Vin × ΔIL × fsw)
Minimum Output Capacitance:
Cout ≈ ΔIL / (8 × fsw × ΔVout)
Power and Input Current:
Pout = Vout × Iout
Iin ≈ Pout / (Vin × Efficiency)
Frequently Asked Questions (FAQ)
Q1: What does this buck converter calculator do?
It estimates duty cycle, inductor value, ripple current, output capacitance, output power, and input current for a step-down DC-DC converter.
Q2: What is a buck converter?
A buck converter is a switching regulator that converts a higher DC input voltage to a lower DC output voltage.
Q3: What ripple current should I choose?
A common starting point is 20% to 40% of output current. Lower ripple requires a larger inductor, while higher ripple reduces inductance but increases stress and output ripple.
Q4: Why is switching frequency important?
Higher switching frequency usually allows smaller inductors and capacitors, but it may increase switching loss, EMI, and layout sensitivity.
Q5: How should I choose the inductor current rating?
The inductor saturation current should be higher than the peak inductor current, typically Iout + ΔIL/2, with proper design margin.
Q6: Is the output capacitor result enough for final design?
No. Real output ripple also depends on capacitor ESR, ESL, load transient requirements, control-loop stability, and PCB layout.
