Power Electronics
Model class: Standard approximation
Buck converter design workspace
Calculate first-pass CCM duty, inductance, ripple current, peak current, and operating boundary for an ideal buck converter.
Interactive engine
Start with the stated conditions.
Values stay in this browser. Choose a representative scenario, then calculate deliberately.
Example ready
Calculate to inspect the result.
The result will identify the direct answer, assumptions, and any warning that changes the next decision.
Assumptions to check
- Continuous conduction mode and ideal switching stage.
- Constant input and output conditions.
- No control-loop, parasitic, transient, or component-loss model.
A power stage begins with operating corners
The ideal buck relationship gives duty and an initial inductance from a selected ripple target. It also reveals the peak and valley inductor current that later drive saturation, current rating, switch stress, and loss checks.
The calculation is intentionally not a complete converter design. A practical stage also needs input range, control-loop compensation, capacitor impedance, switch and diode losses, layout, startup, protection, and bench validation.
Read the boundary result
If valley current reaches zero, the selected condition enters discontinuous conduction and the CCM estimate no longer describes the waveform. Use that warning to change the load, ripple target, or model before selecting parts.
Turn the first-pass values into component checks
The calculated inductance and ripple target are starting values, not a part selection. Check the full input-voltage and load range because the duty ratio, ripple current, peak current, and continuous-conduction boundary all move. Compare peak current with inductor saturation, RMS current with winding loss, and ripple-current capability with the selected capacitor. A converter that works at one nominal point can cross a component or control limit at a different source or load corner.
Keep the ideal power-stage estimate separate from the remaining design work. Switch and diode or synchronous-FET loss, gate drive, current limit, compensation, input impedance, output transient response, startup, short-circuit protection, layout loop area, and EMI each need their own stated evidence. Use this page to frame those questions, then follow vendor guidance and validate a prototype under the actual electrical and thermal envelope. Preserve the operating corner beside every measured waveform.
Common mistakes
- Sizing from one input voltage only.
- Ignoring inductor saturation at peak current.
- Treating ideal duty as a control-loop design.
Model limit and handoff
Validate the full input, load, temperature, component, control-loop, layout, and protection envelope with vendor guidance, simulation, and bench work.
FAQs
Why must output be below input?
This page is the first-pass nonisolated buck model. Other topologies cover different conversion relationships.