Eswitch simple

Eight-channel eswitch — PROTO-PWR3

212 × 116 mm, four-layer prototype with shared LM74800-Q1 AUTO/logic protection and unconditional passive fuse-selected BYPASS. Open eswitch-simple.kicad_pro.

The release is for bare-board first articles and controlled bench testing. See BUILD.md for assembly and ordering, and PROTECTION-REVIEW.md for the engineering review and hardware tests. Neither 40 A continuous operation nor surge survival has been qualified on hardware. Firmware is not supplied.

Power paths

AUTO:   BATT_RAW -- F10 -- LM74800 cutoff -- shared VS -- PROFET -- ATO fuse -- LOAD
BYPASS: BATT_RAW ----------------------------------------------- ATO fuse -- LOAD

One movable ATO fuse per channel, three clips. Pins 1/2/3 are PROFET_OUT/LOAD/RAW. Move the fuse between AUTO and BYPASS only with power disconnected; remove it for OFF. BYPASS/OFF disconnects the load from the PROFET output, avoiding body-diode backfeed. BYPASS has no series electronics and receives raw surges/reversed polarity.

For electronics-fault recovery, disconnect battery and USB, remove F10, move usable channel fuses to BYPASS, then restore power. All AUTO channels may be lost; no extra fixed per-channel fuses are required. Upstream-fuse selectivity and uninterrupted operation are not promised. Shared copper/terminal damage is outside the model.

F10 is a removable Mersen FR14GG50V40 with two MR14SPRING clips and M5 terminals. F9 remains the 2 A logic fuse. AUTO uses BTS7004 on CH1/2, BTS7008 on CH3–7 and BTS7002 on CH8. Maximum ATO fuses: 10/10/5/5/5/5/5/20 A. These are fuse maxima, not validated continuous channel currents. LEDs show AUTO output voltage; BYPASS current is not measured. J11–J18 pin 1 is LOAD+, pin 2 is GND. J5 is 3.3 V bench UART.

The common-source protection targets a +80 V, several-second input event using overvoltage cutoff, not fuse operation or continuous linear clamping. Nominal cutoff is 16.841 V. The four 200 V and two 60 V MOSFETs use individual gate resistors. C27 is 1 µF for the parallel-bank charge pump. The existing sense resistance values remain; R104–R804 use high-power ERJ-PA3 parts for fault-reporting dissipation.

Verification and fabrication

• Native ERC, PCB DRC, unconnected and schematic-parity checks must all be zero.
• Topology model: 52,488 mode/supply combinations and 54 fault/removal cases.
• power-copper-review.json: 60 planar power paths with explicit regression floors.
• power-transition-review.json: real pad-layer connections and local via arrays.
• protection-screen.json and sense-screen.json: reproducible static screens.
• out/redesign/verification.json: source hashes and checks for the packaged revision.

The two-layer LOAD corridors, protected supply spine and raw BYPASS feed are explicitly reserved before routing signals. Geometry checks are not thermal solvers. Manufacturing uses JLC041622-3313, 2 oz inner and outer copper, filled/capped vias and 90 Ω USB differential control. Follow JLCPCB-ORDER.txt exactly.

python3 redesign/generate.py  # explicitly regenerate schematic/BOM after changes
just verify                  # ERC/topology/parity/geometry/physical transitions
just package                 # verified fabrication and portable project ZIPs
just render                  # board views

The saved PCB is authoritative. Routing scripts and out/redesign/protection-* files are development history, not alternative ordering files. Some intermediate candidates intentionally contain errors or disconnected nets. Do not regenerate placement over the finished board. KiCad's Python environment is required for layout scripts; requirements-route-gaps.txt dependencies live in out/py39.

Procurement and installation

bom-draft.csv is the fitted one-board BOM despite its historical filename. ../fab/eswitch-digikey-qty1.csv contains exact MPN/quantity upload rows, without spares. F10 screws, washers and shims are separate mechanical purchases detailed in BUILD.md. Stock and cart acceptance must be checked when ordering.

cost-estimate.json applies historical prices only where known and explicitly lists unpriced parts. Its subtotal is not a complete build price or current quote. Fabrication, assembly, hardware, shipping and taxes are excluded.

Intended installation: Vatrer 300 Ah LiFePO4, separate Victron Orion XS 12/12-70A charger branch, 40 A MRBF eswitch feed and 75 A MRBF charger feed. Use 8 AWG copper positive/negative for the 1 m battery run and 4 mm² positive/negative for the 3 m pump run. CH1/2 with a provisional 10 A fuse is appropriate for the standard 12 V Rule 1500 GPH model; confirm the actual pump. Direct-battery fault coordination, thermal limits, pump transients and surge performance remain hardware tests.