This power-electronics calculator finds the ideal duty cycle and ripple-current inductance for an inverting buck-boost converter.
Physics
Inverting Buck-Boost Converter Calculator
Calculate ideal inverting buck-boost duty cycle and ripple-current inductance.
Calculator
About this calculator
Formula notes
duty = Vout / (Vin + Vout); L = duty x Vin / (ripple current x switching frequency), with an inverted output.
Worked examples
- Example: 12 V input to a 5 V magnitude output at 100 kHz with 500 mA ripple gives a duty of about 29.4% and about 70.6 uH.
- 5 V in and 12 V magnitude out at 200 kHz with 400 mA ripple gives a duty of about 70.6% and about 106 uH.
How to use it
- Enter input and output voltage magnitude.
- Enter the switching frequency and maximum ripple current.
- Read the duty cycle and the required inductance.
Frequently asked questions
Why is the output inverted?
An inverting buck-boost produces a negative output referenced to the input ground, so the calculator reports a signed voltage.
Does this include real-world losses?
No. The equations use the ideal model; diode drops, ESR, and controller losses need separate analysis.
Limits and interpretation
- The equations model the ideal continuous-conduction converter; real losses, parasitics, and control behavior are not included.
- The output is inverted relative to the input ground, so use the signed voltage when wiring.