Calculator Inputs
Example Data Table
| Vin | Vout | Iout | Efficiency | Frequency | Ripple | Use Case |
|---|---|---|---|---|---|---|
| 12 V | 24 V | 2 A | 90% | 100 kHz | 30% | Battery step-up supply |
| 5 V | 12 V | 1 A | 88% | 250 kHz | 25% | Embedded power rail |
| 24 V | 48 V | 3 A | 92% | 75 kHz | 35% | Industrial control supply |
Formula Used
Output power: Pout = Vout × Iout.
Input power: Pin = Pout ÷ efficiency.
Input current: Iin = Pin ÷ Vin.
Ideal duty cycle: D = 1 − Vin ÷ Vout.
Adjusted duty cycle: D = 1 − (Vin − switch drop) ÷ (Vout + diode drop).
Inductor ripple: ΔIL = Iin × ripple percent.
Inductance: L = Vin × D ÷ (ΔIL × switching frequency).
Capacitance: C = Iout × D ÷ (switching frequency × allowed ripple voltage).
Critical inductance: Lcrit = D × (1 − D)² × R ÷ (2 × switching frequency).
Stored energy: E = 0.5 × L × Ipeak².
How to Use This Calculator
Enter the source voltage, target output voltage, and load current. Add expected efficiency, switching frequency, ripple limits, diode drop, switch drop, and capacitor ESR. Press calculate to view duty cycle, inductor size, capacitor size, currents, ripple, losses, and conduction mode guidance.
Use the CSV button for spreadsheet records. Use the PDF button for a simple report. Always compare calculated values with real component ratings, thermal limits, layout quality, and manufacturer data before building hardware.
Advanced Boost Converter Circuit Guide
Purpose
A boost converter raises a lower direct voltage to a higher output voltage. It stores energy in an inductor while the switch is on. It releases that energy through the diode or synchronous device when the switch turns off. This calculator gives a practical first design estimate.
Design Inputs
The most important inputs are source voltage, target voltage, load current, switching frequency, and efficiency. Ripple settings control the inductor and capacitor choices. Lower ripple normally needs larger parts. Higher switching frequency can reduce part size, but it may increase switching loss and heat.
Duty Cycle
The duty cycle shows the switch on time ratio. An ideal circuit ignores losses. Real circuits need more duty because the diode, switch, winding, and layout drop voltage. The adjusted duty cycle gives a stronger estimate for practical design work.
Inductor Choice
The inductor must carry average input current and peak ripple current. Saturation current should exceed the calculated peak current with margin. RMS current also matters because winding loss creates heat. The critical inductance value helps judge continuous conduction operation.
Capacitor Choice
The output capacitor supplies load current during the switch on interval. Its capacitance sets charge ripple. Its ESR adds another ripple component. Low ESR parts often improve noise performance. Voltage rating should exceed the output voltage with safe margin.
Current Stress
The switch, diode, inductor, and capacitor all face pulsed current. Average current alone is not enough. Peak and RMS values are useful for choosing packages, thermal paths, and current ratings. Add margin for startup, load steps, and low input voltage.
Efficiency and Heat
Efficiency affects input current and loss. A lower efficiency estimate gives a safer input current value. Loss becomes heat in real components. Heat depends on conduction loss, switching loss, diode loss, magnetic loss, and board copper area.
Practical Notes
Keep high current loops short. Place input and output capacitors close to switching parts. Use proper grounding. Check diode reverse voltage, switch voltage rating, and controller limits. Validate the final circuit with simulation, prototype measurements, and safe laboratory procedures.
FAQs
What is a boost converter?
A boost converter is a switching power circuit that raises input voltage. It uses an inductor, switch, diode or synchronous rectifier, capacitor, and control method.
Why must output voltage be higher than input voltage?
This circuit is designed for step-up conversion. If output voltage is equal to or lower than input voltage, another converter type may be more suitable.
What duty cycle is too high?
Very high duty cycles can increase current stress, losses, and control difficulty. Many practical designs avoid operating near the maximum limit.
How much inductor ripple is acceptable?
Many early designs use 20% to 40% of average input current. Lower ripple improves current smoothness but usually needs a larger inductor.
Why include diode drop?
The diode drop reduces real output transfer efficiency. Including it makes the duty cycle estimate closer to a practical non-ideal circuit.
Does capacitor ESR matter?
Yes. ESR creates extra voltage ripple from pulsed current. Low ESR capacitors can reduce ripple and improve transient behavior.
What is critical inductance?
Critical inductance estimates the boundary between continuous and discontinuous inductor current. Continuous mode often gives smoother current and simpler ripple prediction.
Can I build directly from these results?
Use these values as starting estimates. Confirm them with datasheets, simulations, thermal checks, layout review, and safe prototype testing.