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.

zen

# 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.

zen

Passive = record(value=typing.Any, dnp=bool)

input_filter = config("input_filter", 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.

zen

# 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.

zen

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

# GOOD
input_filter = config("input_filter", 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()

zen

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 Checks on Power IOs

Every

Power

io gets

voltage_within

matching the datasheet's absolute maximum or recommended operating range.

zen

VCC = io("VCC", Power, checks=voltage_within("2.7V to 36V"))

Help Strings

Use

help=

when it adds integrator-visible meaning that is not already obvious from the name, type, checks, or default. Omit it when it would just restate those fields.

zen

VDD = io("VDD", Power, checks=voltage_within("3.0V to 5.5V"))
GND = io("GND", Ground)
EN = io("EN", Net, help="High to enable the regulator")
input_filter = config("input_filter", Frequency, default="0Hz", optional=True,
    help="Input lowpass cutoff. 0Hz disables the filter.")

.NET

Accessor

Use Power/Ground ios directly as pin connections. Never use

.NET

zen

# 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_within
```
on all
```
Power
```
ios
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

idiomatic-zener

NPX Install

Tags

SKILL.md Content

Idiomatic Zener

No Conditional Instantiation

DNP via Record Pattern

Minimize Component Count

Typed Unit Configs

Computation in Named Functions

Voltage Checks on Power IOs

Help Strings

No
`.NET`
Accessor

Naming

Opinionated Defaults

Checklist

idiomatic-zener

NPX Install

Tags

SKILL.md Content

Idiomatic Zener

No Conditional Instantiation

DNP via Record Pattern

Minimize Component Count

Typed Unit Configs

Computation in Named Functions

Voltage Checks on Power IOs

Help Strings

No .NET Accessor

Naming

Opinionated Defaults

Checklist

No
`.NET`
Accessor