Switch one 5–24 V DC load using a low-side MOSFET and flyback protection. The external-supply design target is 5 A; it is not a qualified rating. Host-supplied operation is a separate, default-disabled prototype mode, limited to 0.5 A only after an upstream allocation is authorized.
Baseline documentation snapshot: 2026-10-11, before the requested connector/protection/usability revision program. New revision features require their own reviewed source and qualification evidence.
This page documents an unqualified engineering study, not a released or tested product. Saved CAD, renders and automated checks do not establish a safe assembly, compatible cable, firmware support or a usable current rating.
Board-specific qualification limits: v22 native/ordinaryassembly0;99checklist unsigned and sourceorder/reverse/backfeed/currentthermal/fuse/host/stock/physical open.
Power off before connecting or changing jumpers. Verify pin 1, signal direction, supply voltage and ground at both ends of every cable. A mechanically fitting connector is not proof of electrical compatibility. If a host pin mapping or current allocation remains unresolved in the design record, do not connect the board until it is resolved.
The following are specification requirements or study assumptions; they are not measured operating ratings. A newer selected-revision note takes precedence over historical draft options.
The design describes the following protection intent. Check the selected schematic and remaining qualification gates before relying on it:
Two independent ideal-diode branches replace the historical diode OR because a silicon/Schottky series diode dissipates substantial power at 5 A. The selected topology blocks static reverse current and reversed external polarity within its stated limits. Finite leakage and switching transients are not zero by definition and must be measured. Never energize AC, opposing input surges, missing/common-ground faults, voltages above the operating contract, or an unlimited short-circuit source. Static opposite inputs differ by at most 48 V; this does not qualify arbitrary transient combinations.
See current review. Retain dual LM74700 ideal-diode branches and60/100VpowerFETs. Existing Q4 V2generic2N7002/SOT23 and V1 Molex connector family retained;0805supports not0402stock dropins,no successor. Current selected v22; retained native/stock/physical qualification limits remain explicit.
Use the configuration and firmware contract for the exact selected revision. Do not copy another module’s socket assignments or assume that an unused pin is available. First-article work must verify source selection, reset/unplug behavior, cable orientation and the actual load or sensor interface before normal operation.
The following are requirements for the next design iterations; this page does not claim they are already fitted:
Documentation route: smoothieware.org/extensions/single-channel-small-mosfet-output.
The 2026-10-11 upgrade program has saved additional candidates v23, v24, v25. These studies preserve the historical design described above. Their connector, LED, mechanical and protection changes are revision-specific and remain unqualified.
See the per-board changes, failures and remaining work and mandatory family specification. Use the source hash and native check for the exact candidate being reviewed; do not infer hardware ratings from a rendered population.
The three additional revisions are v23, v24, v25. They are engineering studies; saved CAD and renders do not release the hardware. The latest candidate is described below. Older baseline notes above remain historical.
e4ab0fa990eb10fda71ce1fa5ed19cc0ccbe57d711c225d9c28621b2c87964af.Applicable protection, current-path, thermal, pinout, cable access and physical tests remain open wherever the linked board record has not verified them. A zero native-error count does not close those gates.
Protected source v25; current PCB SHA-256 86e73634fe77d8f01c5cafe497a2199bd2428e8cfb1ca162667993f7cae7631b. Fresh checks: zero enabled PCB errors/opens/parity and ERC errors; 1 PCB warnings. Electrical geometry, project rules and 73 historical files unchanged. Verified 154 model entries, 17 exports and 12 current population views, all inspected. Full documentation URL readable. PH-host carries 5-12V and is not STEMMA; body partly obscures front legend, rear map retained Inherited native warnings and enabled-rule exclusions remain explicit Physical/thermal/current/connector-fit qualification open No priced or area savings established by annotation candidate.
The final local finishing pass completed with 0 native errors, 30 open connections and 0 schematic-parity differences, using the existing 0.25 mm relevant-net clearance/track-width rules. It connected the EXT_ILIM and REV_LED_R branches; 20 other attempted branches were withheld. The 60 × 50 mm study is unaccepted; no v27 PCB was promoted. The terminal source SHA-256 is daf8872b2d200cb21a626b58461e761fde2943fa74abf534ef78291f1d7e72ef. Its source and terminal diagnostics were copied into a marked remote-recovery input checkpoint while holding the actual source file open. Full routing, the remote zero-violation gate, manufacturing exports and final renders remain incomplete.
New PCB computation uses the pinned remote whole-job runner only. The portable native warning-repair helper is prepared as source; execution and its same-font title repair remain unverified. The remote runner itself must pass its isolated synthetic routing/publication qualification before production repairs continue. Acceptance and fabrication release remain false.
The immutable remote diagnostic run (receipt 2596f59e5d0e4801b6bc372e135b0a23, exit 0) verified the frozen local symbol/footprint closure and explicitly bundled Montserrat Black font. The compact source has 0 rule errors, 30 opens, 0 parity differences and 66 warnings: 16 silkscreen overlaps, 11 silkscreen-over-copper findings, 1 hole-spacing finding, 12 dangling tracks and 26 dangling vias. ERC has zero findings. Diagnostic execution success is not native acceptance.
The native-only power repair (receipt a9a3a0c35b8e49fcb839fdede39d9aec, exit 1) joined the parallel EXT_RAW pads with a 1 mm conductor and reduced opens to 28, with 0 rule errors, 0 parity differences and 66 warnings. All original track identities/nets were retained. The partial result SHA-256 is 31d33ac435c3254ff0a4e4128ec3c3f640331402c7b4042bf9d7089b9f76bad8; it remains unpublished remotely. The EXT_IDEAL join did not reduce opens and was withheld. Native-constrained attempts found no available current-width path for the LOAD_PWR tap/clamp and HOST_RAW supply, and no legal existing-layer transition or clear endpoint for the two HOST_FUSED branches. No clearance, width or layer-count relaxation was applied.
The isolated routing qualification is still unsuccessful: its verified FreeRouting jar requires Java class version 69 (Java 25), while the runner pins Java 21/class version 65. Native-only KiCad work is available with explicit library/font closure; Java routing remains unavailable pending runner dependency reconciliation. The zero-violation publication gate correctly rejected the partial power repair. No v27 source, final manufacturing exports or corrected renders have been published. Acceptance and fabrication release remain false.
The follow-up opposite-face bridge attempt (receipt f163b48875204ef2afa9b3442b65a2a8, exit 1) also ended at 0 rule errors, 28 opens, 0 parity differences and 66 warnings, with no additional accepted branch. The LOAD_PWR sensing resistor has no legal local layer transition; clamp and host-supply opposite-face routing regions remain disconnected at the required 1 mm and 0.8 mm widths. The HOST_FUSED controller transition and decoupling endpoint remain obstructed. Repeating the same endpoints cannot establish completion: component/fanout rearrangement is still needed. Partial SHA-256 166a9507a738c060d7b99b83e0d39575d12b9280db1d625ae4eba1edf6d04525 remains unpublished remotely. The helper’s optional opposite-face strategy never adds copper layers or relaxes native clearance/current widths. No acceptance or fabrication release.