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

instrument / verified-with-binding-errata

# MOSFET Switching Power Loss Estimator

The current ledger marks this instrument verified with errata that must be applied at binding time.

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

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/mosfet-switching-power-loss-estimator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/mosfet-switching-power-loss-estimator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/mosfet-switching-power-loss-estimator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/mosfet-switching-power-loss-estimator/qualification/>)

## Ledger state

The current ledger marks this instrument verified with errata that must be applied at binding time.

**Area**: Electrical & Electronics Engineering — Circuits, Power Systems, Electronics Lab

**Tranche**: tranche-5

**Evidence ID**: t5-177

**Ledger rows**: 1

No ledger note is attached.

## Review findings

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.

### Formula and scope findings

- 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.

### Unit assumptions

- 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.

## Boundary hardening

**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.

## Errata and corrections

### Tranche errata

**conduction_loss_W / total_loss_W** · vector 1

0.0768 / 2.7648

0.768 / 3.456

64×0.012 written as 0.0768 (10× low); switching loss correct

## Inspectable example

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

````
{
  "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."
}
````

## 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_WITH_ERRATA`

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

- `BOUNDARY_HAZARD_CATALOG.json`