Source: https://guthlabs.ai/docs/instruments/mosfet-switching-power-loss-estimator/mechanism/

instrument mechanism / verified-with-binding-errata

# MOSFET Switching Power Loss Estimator mechanism

The inspectable method record for MOSFET Switching Power Loss Estimator, kept separate from implementation and qualification.

Status: **VERIFIED_WITH_ERRATA**Lifecycle: **verified-with-binding-errata**

## Model scope

The loss equations are acceptable as a simplified hard-switching model when their assumptions are explicit. The specification needs an explicit junction-temperature formula, Ta and θJA inputs, explicit total-loss definition, and unambiguous time units. The honest label should also mention omitted output-capacitance, diode/dead-time, leakage, and temperature-dependent RDS(on) effects.

- Pcond=Irms²×RDS(on) is standard when RDS(on) is the effective operating-temperature resistance and Irms is the MOSFET current RMS value.

- Psw≈½×Vin×Iout×(tr+tf)×fsw is a simplified hard-switching linear-overlap estimate, not a universal MOSFET switching-loss formula. It requires the switched voltage, switching current, and valid rise/fall-time definitions; Vin and Iout may not equal those quantities in every converter topology.

- The claimed optional junction-temperature estimate has no formula and lacks ambient temperature and a required thermal-resistance input. It should explicitly define Tj=Ta+Ptotal×θJA, subject to the limitations of θJA.

- The total-loss formula is not explicitly stated; it should be Ptotal=Pcond+Psw before any optional thermal calculation.

## Units and conventions

- RDS(on) is in ohms (Ω), Irms and Iout are in amperes (A), Vin is in volts (V), switching times tr and tf are in seconds (s), and fsw is in hertz (Hz).

- The switching-time inputs must be converted from nanoseconds or other units to seconds before evaluation.

- θJA, if supported, must be in °C/W and ambient temperature Ta must be in °C; the resulting temperature rise is in °C.

- RDS(on) is assumed constant over temperature, gate voltage, current, and switching conditions unless a temperature-corrected value is supplied.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "RDS_on_ohm": 0.012,
    "Irms_A": 8,
    "Vin_V": 48,
    "Iout_A": 8,
    "tr_s": 3e-8,
    "tf_s": 4e-8,
    "fsw_Hz": 200000
  },
  "expected_outputs": {
    "conduction_loss_W": 0.0768,
    "switching_loss_W": 2.688,
    "total_loss_W": 2.7648
  },
  "working": "Pcond = Irms²×RDS(on) = 8²×0.012 = 64×0.012 = 0.0768 W.\\ntr+tf = 0.00000003+0.00000004 = 0.00000007 s.\\nPsw = 0.5×48×8×0.00000007×200000 = 192×0.014 = 2.688 W.\\nPtotal = 0.0768+2.688 = 2.7648 W."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The literal formula accepts negative Iout and produces a negative switching loss instead of rejecting the input or applying a reverse-current model. Extreme magnitudes can also produce Infinity in ordinary JavaScript evaluation, and unlabeled resistance/time units can change the result by orders of magnitude.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/mosfet-switching-power-loss-estimator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/mosfet-switching-power-loss-estimator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/mosfet-switching-power-loss-estimator/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`