CALCULATORS / POWER CONVERSION AND SWITCHING

Buck-converter first sizing

Ideal continuous-conduction buck conversion; losses omitted.

power-electronics-buck.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	duty	inputCurrentA
	0.5	1
	0.625	1.25

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

buck duty physical0.50 ✓ passes

BASELINE INPUTS

input24 Voutput12 Vload2 A

CALCULATED

duty0.5

inputCurrent1 A

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Buck-converter first sizing
# Scope: Ideal continuous-conduction buck conversion; losses omitted.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

input = 24 V
output = 12 V
load = 2 A

duty := output/input
inputCurrent := output*load/input [A]

check buck duty physical: duty <= 1

scenario alternative: input = 19.2 V

Calculated from your source · not saved

Baseline · Baseline

buck duty physical0.50 ✓ passes

alternative · alternative

buck duty physical0.63 ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

duty: duty = output/input
input current: inputCurrent = output*load/input [A]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

input: 24 V
output: 12 V
load: 2 A

Calculated

duty: 0.5
input current: 1 A

Assumptions and limits

Ideal continuous-conduction buck conversion; losses omitted.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Buck-converter first sizing. Inputs: input/output range; load; switching frequency; ripple targets. Outputs: duty; inductance; capacitance; stresses. Model scope: First-order switching models and explicit nonidealities. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: input/output range, load, switching frequency, ripple targets
Outputs: duty, inductance, capacitance, stresses
Modes: calculate, compare, sweep
Drawing: Switching waveforms and loss plots

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS