boost circuit calculator

What this boost circuit calculator does

A boost converter raises voltage from a lower DC source to a higher one. This calculator is built for practical engineering estimates, giving you fast sizing guidance before simulation and prototype testing. Enter your target electrical specs and it returns key values needed for initial component selection.

• Duty cycle needed to reach your output voltage
• Expected input current based on output power and efficiency
• Inductor value from selected ripple target and switching frequency
• Output capacitor estimate from ripple requirement
• Switch peak current for MOSFET/inductor current stress checks

Core equations used

The model assumes continuous conduction mode (CCM) and idealized first-order relationships, with efficiency included as a practical correction:

These equations are widely used for early-stage sizing and sanity checks. Final values should always be validated against real controller behavior, ESR, transient load steps, thermal limits, and control-loop stability.

How to use it effectively

1) Start with realistic efficiency

If you are unsure, 85% to 92% is a common first guess depending on power level and design quality. Lower assumed efficiency yields higher input current and usually larger magnetic and thermal requirements.

2) Pick ripple targets intentionally

A typical inductor ripple target is 20% to 40% of average input current. Lower ripple often means larger inductors. Higher ripple can reduce inductor size but increases peak current stress.

3) Verify duty cycle range

Very high duty cycles (for example above 80%) can be difficult in real hardware due to switching losses, current stress, and control margin. Consider whether your input range and desired output are practical with a single-stage boost.

Example quick design

Suppose you need to convert 12V to 24V at 2A output, switching at 200kHz, and expect 90% efficiency. The calculator returns a duty cycle near 55%, input current around 4.4A, and a moderate inductor value in the tens of microhenries. That gives you an immediate starting point for selecting an inductor current rating and MOSFET current margin.

Component selection tips

• Inductor: Choose saturation current comfortably above calculated peak current (usually 20% to 40% margin).
• MOSFET: Ensure V_DS rating exceeds output voltage with surge margin, and confirm thermal dissipation.
• Diode or synchronous FET: Validate reverse voltage and average/peak current stress.
• Output capacitor: Ripple estimate from capacitance alone is optimistic; ESR can dominate ripple in practice.
• Controller IC: Confirm max duty-cycle capability, current limit behavior, and compensation guidance.

Important limitations

This tool does not replace SPICE simulation or bench validation. It does not include switch/diode drops in waveform detail, inductor DCR, capacitor ESR/ESL, slope compensation constraints, startup behavior, or EMI considerations. Use the results as an engineering baseline, then refine with measured data.