Add voltage margin to BJT, FET, and diodes by ducky64 · Pull Request #483 · BerkeleyHCI/PolymorphicBlocks

ducky64 · 2026-04-27T00:42:11Z

Refactors the capacitor to consistently use the new margin nomenclature, with deprecation path. Default for semiconductor devices is 1.25x.

Refactors examples and improves documentation. The refactored capacitor margin overrides is not meant to be exact with prior.

Resolves #419

Copilot

Pull request overview

Adds explicit voltage rating headroom (“margin”) parameters for semiconductors (BJT/FET/diode) and refactors capacitor voltage derating to a consistent “margin” nomenclature with a deprecation path for the old parameter.

Changes:

Introduces *_voltage_margin parameters for BJTs, FETs, and diodes (default 1.25x) and applies them in parts-table filtering.
Refactors capacitors to use voltage_margin (default 2.0x) while deprecating voltage_rating_derating.
Updates example designs and generated reference artifacts (netlists / svgpcb) to align with the new selection behavior and nomenclature.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
`edg/abstract_parts/AbstractCapacitor.py`	Adds `voltage_margin`, deprecates `voltage_rating_derating`, updates table filtering logic accordingly.
`edg/abstract_parts/AbstractFets.py`	Adds `drain_voltage_margin` and applies it to Vds rating selection.
`edg/abstract_parts/AbstractDiodes.py`	Adds `reverse_voltage_margin` and applies it to Vr rating selection.
`edg/abstract_parts/AbstractBjt.py`	Adds `collector_voltage_margin` and applies it to Vce rating selection.
`examples/test_usb_source_measure.py`	Migrates capacitor refinements to `voltage_margin` and adjusts shared diode part selection.
`examples/test_robotcrawler.py`	Migrates capacitor refinement to `voltage_margin`.
`examples/test_iot_led_driver.py`	Migrates capacitor refinement to `voltage_margin` and updates comment.
`examples/test_iot_blinds.py`	Migrates capacitor refinements to `voltage_margin`.
`examples/test_fcml.py`	Updates class-level capacitor refinement to `voltage_margin`.
`examples/test_can_adapter.py`	Migrates capacitor refinement to `voltage_margin`.
`examples/test_bldc_controller.py`	Migrates capacitor refinements to `voltage_margin`.
`examples/UsbSourceMeasure/UsbSourceMeasure.svgpcb.js`	Updates generated PCB placement/footprints consistent with new selected parts.
`examples/UsbSourceMeasure/UsbSourceMeasure.net.ref`	Updates reference netlist to reflect newly selected diode parts/footprints.
`examples/IotDisplay/IotDisplay.net.ref`	Updates reference netlist diode parts consistent with new voltage headroom rules.
`examples/Datalogger/Datalogger.net.ref`	Updates reference netlist diode parts consistent with new voltage headroom rules.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-04-27T00:47:13Z

+                (["bldc_drv", "vm_cap_bulk", "cap", "voltage_margin"], 1.5),  # allow using a 50V cap
+                (["bldc_drv", "cp_cap", "voltage_margin"], 1.5),  # allow using a 50V cap


These voltage_margin values relax the headroom compared to the previous derating of 0.6 (which implied ~1.667x via 1/0.6). If this PR is meant to be a pure rename/refactor, consider using ~1.667 here to preserve behavior, or document that the headroom is intentionally reduced.

Copilot · 2026-04-27T00:47:14Z

+        if not math.isnan(self.get(self.voltage_rating_derating)):
+            derated_voltage = self.get(self.voltage) / self.get(self.voltage_rating_derating)
+            warnings.warn(
+                f"voltage_rating_derating is deprecated and should be replaced with voltage_margin which has inverted semantics",
+                DeprecationWarning,
+            )
+            # 2.0 must be sync'd up with the default value
+            assert self.get(self.voltage_margin) == 2.0, "cannot use both voltage_rating_derating and voltage_margin"
+        else:


warnings.warn(..., DeprecationWarning) is executed inside _row_filter, which runs once per candidate table row. If voltage_rating_derating is set (including from internal code paths), this will likely emit the same warning many times and significantly slow / spam builds. Consider emitting the deprecation warning once per instance (eg, in __init__/generate) or gating it behind a self._warned_voltage_derating flag, and set an appropriate stacklevel so the warning points to the user callsite.

Copilot · 2026-04-27T00:47:14Z

                (["reg_v5", "power_path", "in_cap", "cap", "exact_capacitance"], False),
-                (["reg_v5", "power_path", "in_cap", "cap", "voltage_rating_derating"], 0.85),
-                (["reg_v12", "cf", "voltage_rating_derating"], 0.85),
+                (["reg_v5", "power_path", "in_cap", "cap", "voltage_margin"], 1.1),
+                (["reg_v12", "cf", "voltage_margin"], 1.1),
                (["conv", "power_path", "in_cap", "cap", "exact_capacitance"], False),
-                (["conv", "power_path", "in_cap", "cap", "voltage_rating_derating"], 0.85),
+                (["conv", "power_path", "in_cap", "cap", "voltage_margin"], 1.1),


PR description indicates this is primarily a nomenclature refactor, but the numeric conversion here is not equivalent to the previous derating factors (eg, derating 0.85 corresponds to margin ~1.176 via 1/0.85, not 1.1). If the intent is to preserve prior headroom behavior, set voltage_margin to the inverse of the removed voltage_rating_derating values; otherwise consider documenting that the voltage headroom constraints are being relaxed.

Copilot · 2026-04-27T00:47:14Z

+                (["control", "snub_c", "cap", "voltage_margin"], 1.5),  # allow use of a 50V basic part caps
+                (["control", "ifilt", "c", "voltage_margin"], 1.5),


This changes the effective headroom vs the previous derating value (0.60 implied ~1.667x headroom via 1/0.60, but voltage_margin=1.5 is only 1.5x). If this PR is intended as a pure nomenclature refactor, consider setting voltage_margin to ~1.667 to preserve prior behavior, or add a note that the constraint is being relaxed.

Copilot · 2026-04-27T00:47:14Z

-                    ["reg_3v3", "power_path", "in_cap", "cap", "voltage_rating_derating"],
-                    0.80,
-                ),  # use a 1206 25 oe 35v part
+                (["reg_3v3", "power_path", "in_cap", "cap", "voltage_margin"], 1.25),  # use a 1206 25 oe 35v part


Typo in the comment: "25 oe 35v" should be "25 or 35V".

Suggested change

(["reg_3v3", "power_path", "in_cap", "cap", "voltage_margin"], 1.25), # use a 1206 25 oe 35v part

(["reg_3v3", "power_path", "in_cap", "cap", "voltage_margin"], 1.25), # use a 1206 25 or 35V part

Copilot · 2026-04-27T00:47:15Z

                (["reg_14v", "inductor", "part"], "CBC3225T220KR"),
                (["reg_14v", "inductor", "manual_frequency_rating"], Range(0, 17e6)),  # 17MHz self-resonant
-                (["reg_14v", "out_cap", "cap", "voltage_rating_derating"], 0.85),
+                (["reg_14v", "out_cap", "cap", "voltage_margin"], 1.1),


This voltage_margin is not the direct inverse of the previous derating factor (0.85 -> margin ~1.176 via 1/0.85, not 1.1). If the intent is to keep the same voltage headroom behavior while renaming the parameter, consider using ~1.176 here or documenting that the constraint is being relaxed.

ducky64 added 6 commits April 26, 2026 13:33

deprecate old style and add new style

385a6fd

Update AbstractCapacitor.py

1e29739

add voltage margin

eb3a810

rebaseline

71b0b50

update

29cf984

Update AbstractCapacitor.py

ec5a06d

ducky64 requested a review from Copilot April 27, 2026 00:42

Copilot started reviewing on behalf of ducky64 April 27, 2026 00:42 View session

Copilot AI reviewed Apr 27, 2026

View reviewed changes

Update test_iot_led_driver.py

fa63556

ducky64 merged commit 3f0f5ce into master Apr 27, 2026
12 checks passed

ducky64 deleted the margin branch April 27, 2026 01:01

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Add voltage margin to BJT, FET, and diodes#483

Add voltage margin to BJT, FET, and diodes#483
ducky64 merged 7 commits intomasterfrom
margin

ducky64 commented Apr 27, 2026 •

edited

Loading

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI Apr 27, 2026

Uh oh!

Copilot AI Apr 27, 2026

Uh oh!

Copilot AI Apr 27, 2026

Uh oh!

Copilot AI Apr 27, 2026

Uh oh!

Copilot AI Apr 27, 2026

Uh oh!

Copilot AI Apr 27, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

		(["bldc_drv", "vm_cap_bulk", "cap", "voltage_margin"], 1.5), # allow using a 50V cap
		(["bldc_drv", "cp_cap", "voltage_margin"], 1.5), # allow using a 50V cap

		(["control", "snub_c", "cap", "voltage_margin"], 1.5), # allow use of a 50V basic part caps
		(["control", "ifilt", "c", "voltage_margin"], 1.5),

	(["reg_3v3", "power_path", "in_cap", "cap", "voltage_margin"], 1.25), # use a 1206 25 oe 35v part
	(["reg_3v3", "power_path", "in_cap", "cap", "voltage_margin"], 1.25), # use a 1206 25 or 35V part

Conversation

ducky64 commented Apr 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Copilot AI Apr 27, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 27, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 27, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 27, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 27, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Apr 27, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

ducky64 commented Apr 27, 2026 •

edited

Loading