Spice Simulation

Use a focused testbench such as <package>/testbench/test_<scenario>.zen for one behavior: startup, enable, a protection threshold, or current limit. Reuse an existing bench when it covers the request. Run it with pcb sim <file>.zen; a separate dummy simulation is only useful when diagnosing setup problems.

Model and testbench

The leaf component needs spice_model=SpiceModel(...). Obtain a vendor model or, when appropriate, use a behavioral model with explicit limitations. Match nets to the subcircuit's declared terminal order:

Component(
    name="MyPart",
    symbol=Symbol(library="MyPart.kicad_sym"),
    pins={"VIN": VIN, "VOUT": VOUT, "GND": GND},
    spice_model=SpiceModel(
        "MyPart.lib",
        "MyPart_SUBCKT",
        nets=[VIN, VOUT, GND],
        args={},
    ),
)

Instantiate the module under test and needed loads/passives in Zener. Put sources, waveforms, analysis, and plot commands in the raw ngspice setup string of a top-level Simulation:

load("@stdlib/properties.zen", "Simulation")

Simulation(
    name="SIM",
    setup="""
V_IN VIN GND DC 12
.control
  tran 10u 10m
  set hcopydevtype = svg
  hardcopy output/startup.svg v(VIN) v(VOUT)
.endc
""",
)

Adapt the source and analysis to the behavior; for example, PULSE(...) for enable timing or PWL(...) for a changing input. Write plots under testbench/output/ and inspect only the signals needed to establish the result. Distinguish a model or simulator failure from an electrical finding, and state what the model and analysis actually verify.