PWM Duty Cycle Inputs
Choose a calculation mode, enter known values, and generate a detailed switching analysis.
Example Data Table
This example uses a 12 V PWM signal driving a resistive load with a 60% duty cycle at 20 kHz.
| Mode | Duty Cycle | Frequency | Period | High Time | Low Time | Average Voltage | RMS Voltage |
|---|---|---|---|---|---|---|---|
| Duty Cycle + Frequency | 60% | 20 kHz | 50 µs | 30 µs | 20 µs | 7.2 V | 9.2952 V |
| High Time + Low Time | 25% | 5 kHz | 200 µs | 50 µs | 150 µs | 3 V | 6 V |
| High Time + Period | 40% | 10 kHz | 100 µs | 40 µs | 60 µs | 4.8 V | 7.5895 V |
Formula Used
Duty Cycle (%) = (High Time ÷ Period) × 100
Period = High Time + Low Time
Frequency = 1 ÷ Period
High Time = Period × Duty Ratio
Low Time = Period − High Time
Average Voltage = (Vhigh × Duty Ratio) + (Vlow × (1 − Duty Ratio))
RMS Voltage = √[(Vhigh² × Duty Ratio) + (Vlow² × (1 − Duty Ratio))]
Average Current = Average Voltage ÷ Resistance
RMS Current = RMS Voltage ÷ Resistance
Average Power = RMS Voltage² ÷ Resistance
How to Use This Calculator
- Select the input mode that matches your known PWM values.
- Choose the correct time and frequency units before entering data.
- Enter high voltage, low voltage, and optional load resistance.
- Click the calculate button to generate timing, voltage, current, and power results.
- Review the waveform plot and detailed results table for verification.
- Use the CSV or PDF buttons to export the calculated output for testing notes or reports.
Frequently Asked Questions
1) What is PWM duty cycle?
PWM duty cycle is the percentage of one switching period spent in the ON state. It controls average delivered voltage, power, brightness, speed, or heat in many electronic systems.
2) What does a 50% duty cycle mean?
A 50% duty cycle means the signal stays high for half of each period and low for the other half. With a zero-volt low level, average voltage becomes half of the high-level voltage.
3) Why are average voltage and RMS voltage different?
Average voltage reflects the mean DC-equivalent level over time. RMS voltage reflects effective heating or power capability in resistive loads, so it is usually more useful for current and power estimates.
4) Can the low-state voltage be non-zero?
Yes. Some switching circuits, drivers, or offset signals do not fall to zero during the OFF state. This calculator includes both high-level and low-level voltage to model that behavior accurately.
5) What is mark-space ratio?
Mark-space ratio compares ON time to OFF time. A ratio above 1 means the signal stays high longer than it stays low. It is useful when tuning switching waveforms and timing symmetry.
6) How does frequency affect PWM applications?
Frequency changes how often switching occurs. Higher frequency can reduce ripple and audible noise, but it may increase switching losses, heat, and electromagnetic interference in practical circuits.
7) Can duty cycle be 0% or 100%?
Yes. At 0%, the signal is always low. At 100%, the signal is always high. In those edge cases, one timing interval becomes zero and the mark-space ratio becomes infinite or zero.
8) Is this calculator enough for final hardware validation?
It is excellent for design checks, fast estimation, and documentation. Final validation should still include oscilloscope measurements, component tolerances, switching losses, rise times, and real load behavior.