Idiomatic Zener Prescriptive style rules for .zen code. These apply to all modules, reference designs, and board files. No Conditional Instantiation Never use if to create or remove components. Always instantiate every component. Use dnp= to control whether it is populated. This applies to modules, boards, and reference designs, including optional feature blocks.

BAD

if add_decoupling: Capacitor(name="C_VDD", value="100nF", package="0402", P1=VCC, P2=GND)

GOOD

Capacitor(name="C_VDD", value="100nF", package="0402", P1=VCC, P2=GND) DNP via Record Pattern For optional subcircuits controlled by a config, use a record to pair values with DNP state. A zero/disabled config value means dnp=True with placeholder values. Passive = record(value=typing.Any, dnp=bool) input_filter = config(Frequency, default="0Hz", optional=True, help="Input lowpass cutoff. 0Hz disables the filter.") def input_rc(f): dnp = f <= Frequency("0Hz") r = e96(Resistance("100ohm") if not dnp else Resistance("0ohm")) c = e24(1 / (2 * PI * r * f) if not dnp else Capacitance("100pF")) return Passive(value=r, dnp=False), Passive(value=c, dnp=dnp) input_r, input_c = input_rc(input_filter) Resistor(name="R_IN", value=input_r.value, dnp=input_r.dnp, package="0402", P1=A, P2=B) Capacitor(name="C_IN", value=input_c.value, dnp=input_c.dnp, package="0402", P1=B, P2=GND) Minimize Component Count Fewer parts = simpler BOM, easier assembly, lower cost. Prefer value-switching over duplicate components. When a config selects between discrete options, use a single component with a computed value — don't instantiate multiple components with opposing DNP conditions.

BAD: two resistors, one always DNP

Resistor(name="R_STRAP_HI", value="10kohm", P1=STRAP, P2=VCC, dnp=mode != "HIGH") Resistor(name="R_STRAP_LO", value="100kohm", P1=STRAP, P2=VCC, dnp=mode != "LOW")

GOOD: one resistor, value changes with config

_strap_value = { Mode("HIGH"): "10kohm", Mode("LOW"): "100kohm", Mode("FLOAT"): "10kohm" }[mode] Resistor(name="R_STRAP", value=_strap_value, P1=STRAP, P2=VCC, dnp=mode == Mode("FLOAT")) Leverage internal pull-ups/pull-downs. Many ICs have internal bias on strap pins. If the default state uses the internal pull, don't add an external resistor — just DNP the single resistor for that case. Typed Unit Configs Use physical types from @stdlib/units.zen for configs. Expose one meaningful parameter (e.g. cutoff frequency), not raw R/C values. Use enum() only for discrete design choices.

BAD

config("filter_r", str, default="10ohms")

GOOD

input_filter = config(Frequency, default="0Hz", optional=True, help="Input lowpass cutoff. 0Hz disables the filter.") Computation in Named Functions Put calculations in named functions with datasheet references. Snap to E-series with e96() / e24() . def load_r(v_out, v_sense): """Datasheet §8.1.1 / Eq 4: V_OUT = V_SENSE × gm × R_L""" GM = Current("200uA") / Voltage("1V") return e96(v_out / (v_sense * GM)) Voltage on Power IOs Every Power io declares its voltage range via the template. VCC = io(Power(voltage="2.7V to 36V")) Help Strings Use help= when it adds integrator-visible meaning that is not already obvious from the name, type, or default. Omit it when it would just restate those fields. VDD = io(Power(voltage="3.0V to 5.5V")) GND = io(Ground) EN = io(Net, help="High to enable the regulator") input_filter = config(Frequency, default="0Hz", optional=True, help="Input lowpass cutoff. 0Hz disables the filter.") No .NET Accessor Use Power/Ground ios directly as pin connections. Never use .NET .

BAD

Capacitor(name="C_VDD", value="100nF", P1=VCC.NET, P2=GND.NET)

GOOD

Capacitor(name="C_VDD", value="100nF", P1=VCC, P2=GND) Naming Beyond the standard conventions (UPPERCASE io, lowercase config): Element Convention Example Internal nets _ prefix _VREF , _XI , _RBIAS Component names Uppercase functional prefix R_LOAD , C_VDD , U_LDO Differential pairs _P / _N suffixes IN_P , IN_N (not _PLUS / _MINUS ) Opinionated Defaults Don't expose configs for implementation details integrators shouldn't tune: decoupling cap values, passive package sizes, test point style. Do expose configs for things integrators legitimately need to change: filter cutoffs, output voltage, gain settings, enable/disable optional subcircuits. Checklist No if guards on instantiation — always instantiate, use dnp= No .NET accessor — use ios directly No str configs for physical values — use typed units Calculations in named functions with e96() / e24() Voltage range on all Power ios via template Add help= only when it clarifies non-obvious integrator-facing meaning Diff pairs use _P / _N , not _PLUS / _MINUS Internal nets prefixed with _ Minimize component count — value-switch, leverage internal bias When renaming components or nets, keep existing

pcb:sch

comments in sync Omit no_connect pins from Component() pins