Duty Cycle / PWM Average Voltage Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Electrical & Electronics Engineering — Circuits, Power Systems, Electronics Lab

Tranche

tranche-5

Evidence ID

t5-216

Ledger rows

1

No ledger note is attached.

Review findings

The core average and period formulas are standard under the stated assumptions, but the specification is not implementation-complete because percent-to-fraction conversion, on/off-time formulas, input constraints, and frequency units are not explicitly defined. The honest label should state that this is an ideal PWM arithmetic calculator producing average (DC-component) voltage, not a real-load or RMS-voltage calculator.

Formula and scope findings

• The average-voltage formula is correct only when D is a unitless fraction from 0 to 1, but the declared input is duty cycle in percent; the implementation must convert D_percent to D_percent/100 before applying the formula.
• The declared outputs include on-time and off-time, but formulas are missing; they should be Ton=D×T and Toff=(1−D)×T.
• The frequency-to-period formula T=1/f is correct for frequency expressed in hertz and period expressed in seconds, but the required frequency unit is not specified.

Unit assumptions

• Duty cycle inputs are interpreted as percent and converted by D=duty_cycle_percent/100.
• Vhigh and Vlow use the same voltage unit, producing Vavg in that unit.
• Frequency is in hertz (cycles per second), period is in seconds, and on/off times are in seconds.
• The PWM waveform is assumed ideal and switches between Vhigh and Vlow with no transition time.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

A zero-frequency input makes T=1/f a division by zero, leaving period and on/off times undefined. The instrument must reject frequency=0 rather than return a misleading numeric result. The specification also leaves the duty-cycle percent-versus-fraction convention implicit, creating a substantial interpretation hazard.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "duty_cycle_percent": 25,
    "Vhigh_V": 12,
    "Vlow_V": 0,
    "frequency_Hz": 1000
  },
  "expected_outputs": {
    "Vavg_V": 3,
    "period_s": 0.001,
    "on_time_s": 0.00025,
    "off_time_s": 0.00075
  },
  "working": "D=25/100=0.25. Vavg=D×Vhigh+(1−D)×Vlow=0.25×12+(1−0.25)×0=3+0=3 V. T=1/f=1/1000=0.001 s. Ton=D×T=0.25×0.001=0.00025 s. Toff=(1−D)×T=0.75×0.001=0.00075 s."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json