Design an inverting buck-boost converter by calculating duty cycle, inductance, output capacitance, switch stress, and power budget.
The inverting buck-boost converter is a fundamental DC-DC topology that produces a negative output voltage from a positive input. Unlike the standard buck (step-down) or boost (step-up) converter, the inverting buck-boost can produce an output magnitude either greater or less than the input, making it the most versatile single-switch topology.
This converter is widely used to generate negative supply rails for op-amps, analog circuits, and audio systems. It can also be found in battery-powered devices where a negative rail is needed alongside the main positive supply.
This Inverting Buck-Boost Converter Calculator computes the duty cycle, minimum inductance for continuous conduction mode, output capacitance for a specified ripple tolerance, switch voltage stress, input and peak currents, power loss, and efficiency metrics. Preset buttons cover typical applications from 5 V logic supplies to 48 V industrial systems. A converter topology comparison table helps you choose the right approach for your design.
Use the preset examples to load common values instantly, or type in custom inputs to see results in real time. The output updates as you type, making it practical to compare different scenarios without resetting the page.
This calculator improves speed and consistency while reducing avoidable mistakes in practical workflows. This tool is designed for quick, accurate results without manual computation. Whether you are a student working through coursework, a professional verifying a result, or an educator preparing examples, accurate answers are always just a few keystrokes away.
Duty Cycle: D = |Vout| / (Vin + |Vout|) Output Power: Pout = |Vout| × Iout Input Power: Pin = Pout / η Min Inductance: L_min = (Vin × D) / (2 × fsw × ΔI_L) Switch Voltage: V_sw = Vin + |Vout| Output Capacitor: C_out = Iout × D / (fsw × Vout × ΔV/V)
Result: D = 29.4%, L_min = 17.6 µH, V_sw = 17 V, Pout = 5 W
A 12 V to −5 V inverting converter at 1 A output runs at ~29% duty cycle and requires a 17+ µH inductor and a MOSFET rated for at least 17 V.
Use consistent units throughout your calculation and verify all assumptions before treating the output as final. For professional or academic work, document your input values and any conversion standards used so results can be reproduced. Apply this calculator as part of a broader workflow, especially when the result feeds into a larger model or report.
Most mistakes come from mixed units, rounding too early, or misread labels. Recheck each final value before use. Pay close attention to sign conventions — positive and negative inputs often produce very different results. When working with multiple related calculations, keep intermediate values available so you can trace discrepancies back to their source.
Enter the most precise values available. Use the worked example or presets to confirm the calculator behaves as expected before entering your real data. If a result seems unexpected, compare it against a manual estimate or a known reference case to catch input errors early.
The topology reverses the inductor's voltage during the off-time, delivering current to the output capacitor with reversed polarity. Understanding this concept helps you apply the calculator correctly and interpret the results with confidence.
In CCM, the inductor current never reaches zero during a switching cycle. CCM is preferred for lower ripple and predictable behavior.
Higher frequency allows smaller L and C but increases switching losses. Typical range: 100 kHz to 500 kHz for most applications.
During the off-time, the inductor voltage reverses and adds to the input voltage across the switch — the MOSFET must be rated accordingly. Use this as a practical reminder before finalizing the result.
No — for positive output use a buck, boost, or SEPIC converter. The inverting buck-boost inherently produces negative output.
Typical efficiency ranges from 75% to 90%, depending on component selection, operating point, and switching frequency. Keep this note short and outcome-focused for reuse.