PWM Voltage Calculator Formula

Understand the math behind the pwm voltage calculator. Each variable explained with a worked example.

Use the PWM Voltage Calculator

Formulas Used

Average Voltage

v_avg = v_peak * duty_cycle_pct / 100

RMS Voltage

v_rms = v_peak * sqrt(duty_cycle_pct / 100)

Power Ratio vs DC

power_ratio = duty_cycle_pct

Variables

VariableDescriptionDefault
v_peakPeak Voltage (Logic High)(V)3.3
duty_cycle_pctDuty Cycle(%)75

How It Works

PWM Average Voltage

A PWM signal with fixed amplitude and variable duty cycle produces an average voltage proportional to the duty cycle.

Formulas

V_avg = V_peak x Duty Cycle

V_rms = V_peak x sqrt(Duty Cycle)

When filtered through a low-pass filter, the PWM signal approximates a DC voltage equal to V_avg. This principle drives motor controllers, dimmers, and digital-to-analog conversion.

Worked Example

3.3 V logic level at 75% duty cycle.

v_peak = 3.3duty_cycle_pct = 75
  1. 01Average voltage: 3.3 x 0.75 = 2.475 V
  2. 02RMS voltage: 3.3 x sqrt(0.75) = 3.3 x 0.866 = 2.858 V
  3. 03Power is 75% of continuous DC

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