Zener Diode Regulator Design Calculator mechanism

Model scope

The advertised model is a basic constant-voltage shunt-regulator calculation, consistent with the honest label, but the current notation, voltage-range handling, power formulas, and required Pmax input must be specified before implementation. As written, the specification is not sufficiently unambiguous for a PASS verdict.

• The symbol Izmin_to_max is undefined. A single resistor-design equation should use the minimum input voltage, maximum load current, and minimum required Zener current: R=(Vin_min−Vz)/(Iload_max+Izmin).
• Using an unspecified Vin rather than Vin_min can fail to maintain the required minimum Zener current at low input voltage and high load current.
• The specification does not provide a formula for resistor power. Under the constant-Vz model, worst-case resistor dissipation is approximately (Vin_max−Vz)^2/R.
• The specification does not provide a formula for Zener power. Under the constant-Vz model, worst-case Zener dissipation is approximately Vz*((Vin_max−Vz)/R−Iload_min), normally evaluated at maximum input and minimum load.
• Pz≤Pmax cannot be evaluated because Pmax is not listed as an input.
• The output 'resistor power rating' is ambiguous: calculated dissipation is not itself a component rating; the selected resistor rating must be at least the calculated dissipation, with any required derating margin specified.

Units and conventions

• All voltages are in volts, currents are in amperes, resistance is in ohms, and powers are in watts.
• Iload and Izmin must be converted from mA to A before calculation; for example, 25 mA means 0.025 A.
• The test vectors interpret the intended design inputs as Vin_min, Vin_max, Iload_min, Iload_max, Izmin, and Pz_max.
• The Zener voltage is treated as constant at Vz; dynamic resistance, tolerance, temperature dependence, and knee-voltage behavior are ignored.
• The design equation uses Vin_min, Iload_max, and Izmin. Maximum Zener power is evaluated at Vin_max and Iload_min.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "Vin_min_V": 12,
    "Vin_max_V": 15,
    "Vz_V": 5.1,
    "Iload_min_A": 0,
    "Iload_max_A": 0.02,
    "Izmin_A": 0.005,
    "Pz_max_W": 0.5
  },
  "expected_outputs": {
    "R_ohm": 276,
    "resistor_dissipation_max_W": 0.3551,
    "zener_dissipation_max_W": 0.1829,
    "zener_power_check": "PASS"
  },
  "working": "R=(12−5.1)/(0.005+0.020)=6.9/0.025=276 ohm. At maximum input, resistor dissipation=(15−5.1)^2/276=9.9^2/276=98.01/276=0.3551 W. At maximum input and zero load, Iz=(15−5.1)/276−0=9.9/276=0.03587 A. Pz=5.1×0.03587=0.1829 W. Since 0.1829≤0.5, the Zener check passes."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The model produces undefined results when Izmin+Iload=0 and produces negative, physically invalid resistance and power when Vin<Vz or when a signed-current convention is used without explicit handling.

Other records

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