Embedded, Digital, and Interfaces
Model class: Exact ideal relationship
PWM frequency and resolution planner
Calculate ideal edge-aligned PWM frequency, duty steps, and effective duty resolution from timer clock, prescaler, and counter top.
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.
How much does each input matter?
Each row holds every other input fixed at its current value and moves one input by ±10%, using the same model as the main result. It identifies which input is the binding lever, not a full tolerance stack.
Assumptions to check
- The entered PWM-timer-planner values represent the stated operating condition.
- This exact ideal relationship is evaluated in the declared lumped or first-pass model.
- A PWM-timer-planner calculation is not a component qualification or safety approval.
What this PWM-timer-planner calculation establishes
Calculate ideal edge-aligned PWM frequency, duty steps, and effective duty resolution from timer clock, prescaler, and counter top. The useful result is the stated electrical quantity and the decision it supports, not an unstated claim about a finished product. This engine keeps the governing relationship visible so an input, unit, condition, or model boundary can be reviewed before a value becomes a component or layout choice.
PWM frequency is timer clock divided by prescaler times duty steps, where duty steps equal the counter top value plus one; effective resolution is the base-2 logarithm of the duty steps. Treat the number as a first-pass result for the declared operating point. When a source, load, temperature, frequency, waveform, component tolerance, or measurement condition changes, repeat the calculation at the relevant corner rather than assuming the nominal answer persists.
Worked decision context
48 MHz edge-aligned PWM with prescaler 1 and top 4799 gives 10 kHz and 4800 duty steps, about 12.23 effective bits. That example verifies the equation and illustrates the scale of the result, but it does not select a part by itself. Compare the result with available values, ratings, tolerance bands, and the receiving circuit or physical environment before implementation.
Use the primary output to identify the binding constraint. If it leaves little margin, document which input dominates and use selected-part data, a higher-fidelity model, simulation, or measurement. This is especially important when a small numerical difference changes a thermal, timing, noise, or reliability decision.
Limits and validation handoff
This is the ideal edge-aligned timer relationship for one prescaler and counter-top pair. Dead-time insertion, center-aligned modes, and clock-source tolerance change the achievable result. The calculation does not silently include omitted parasitics, installation conditions, manufacturing variation, or product policy. Those conditions can be decisive even when the arithmetic is exact for the selected model.
Record inputs, units, model assumptions, and the intended decision with the result. Verify the leading risk against the selected component data sheet and a representative measurement when the circuit has consequential energy, high voltage, safety, compliance, or reliability requirements.
Common mistakes
- Treating the PWM-timer-planner result as a guaranteed operating limit rather than a first-pass exact ideal relationship estimate.
- Mixing a data-sheet value measured under one condition with this PWM-timer-planner calculation performed at another.
- Selecting a component before checking the boundary this calculation names: this is the ideal edge-aligned timer relationship for one prescaler and counter-top pair. Dead-time insertion, center-aligned modes, and clock-source tolerance change the achievable result.
Model limit and handoff
Keep the entered PWM-timer-planner conditions with the calculation, then validate the binding limit using the selected component, physical implementation, and representative operating corner.
FAQs
Is this PWM-timer-planner result sufficient to approve a design?
No. It applies exact ideal relationship reasoning to the entered PWM-timer-planner values and names the checks that still need selected-part data, a higher-fidelity model, or measurement. This is the ideal edge-aligned timer relationship for one prescaler and counter-top pair. Dead-time insertion, center-aligned modes, and clock-source tolerance change the achievable result.
What does this PWM-timer-planner calculator assume that could make the result wrong?
PWM frequency is timer clock divided by prescaler times duty steps, where duty steps equal the counter top value plus one; effective resolution is the base-2 logarithm of the duty steps. If the entered values do not match the real operating condition, the result no longer describes the actual circuit.
Where should this PWM-timer-planner result go next?
Compare this PWM-timer-planner result with Oscillator and clock accuracy budgets, then use the stated next decision below the calculator to move from this first-pass number toward an implementation.