Buck / Boost Converter Calculator

Complete design tool for DC-DC converters with visualization, component selection, and efficiency analysis

Calculator
Design Guide
Components
Analysis

Converter Parameters

20 kHz 500 kHz 1000 kHz

Results & Circuit

Circuit Diagram

Duty Cycle
--
%
Inductance
--
µH
Capacitance
--
µF
Peak Current
--
A

Common Applications

USB Charger
12V to 5V @ 2.4A
Car Audio
24V to 12V @ 100W
Solar Boost
5V to 12V @ 50W
Industrial
48V to 24V @ 200W

Design Equations

Parameter Buck Converter Boost Converter
Duty Cycle (D) D = Vout / Vin D = 1 - (Vin / Vout)
Inductor Current IL = Iout IL = Iin = Iout / (1-D)
Inductor Ripple Current ΔIL = 0.3 × IL (30% ripple)
Inductance (L) L = (Vin - Vout) × D / (fsw × ΔIL) L = Vin × D / (fsw × ΔIL)
Output Capacitor Cout = ΔIL / (8 × fsw × ΔVout) Cout = Iout × D / (fsw × ΔVout)
Input Capacitor Cin = Iin × D / (fsw × ΔVin)

Design Tips

  • Use 20-40% ripple current for optimal size/efficiency tradeoff
  • Higher switching frequency = smaller components but lower efficiency
  • Add 20% margin to calculated component values
  • Consider ESR (Equivalent Series Resistance) of capacitors
  • Use proper heatsinking for MOSFETs and diodes

Waveform Analysis

Component Selection

Inductor

Core Types: Ferrite, Powdered Iron, Iron Alloy

Selection Criteria: Current rating, Saturation current, DC resistance

Recommended: Shielded drum core for EMC

MOSFET

Types: N-channel, P-channel

Parameters: Rds(on), Vds, Qg, Gate charge

Recommended: Low Rds(on) for efficiency

Diode

Types: Schottky, Fast recovery, Ultra-fast

Parameters: Forward voltage, Reverse recovery time

Recommended: Schottky for low Vf

Capacitor

Types: Ceramic, Electrolytic, Polymer

Parameters: ESR, Ripple current rating, Voltage rating

Recommended: Low ESR for output filtering

Efficiency Analysis

Power Loss
--
W
Heat Dissipation
--
W
Required Heatsink
--
°C/W

Thermal Analysis

°C
°C
Ω

Thermal Considerations

  • MOSFET junction temperature should stay below 150°C
  • Inductor core temperature should stay below 100°C
  • Add thermal vias under hot components
  • Consider forced air cooling for high power designs