Every silicon architecture considered for the driver-free USB-C industrial service jack, scored against the 14 PRD requirements — with the rejected paths and why they were rejected.
Standing verdict — 23 Apr 2026, unchanged
Artery AT32F437VGT7 + Microchip KSZ8563RNXI
~$11.40 key silicon @1K · $19–23 full BOM @1K · under $18 @10K · both industrial-temp, both Western-stocked
The constraint that decides everything: 3 network interfaces (USB + 2× RJ45) with independent link states and per-interface filtering. Only HPM6750 and i.MX RT1176 put two Ethernet MACs on one die at ~$12–18. Anything cheaper must be single-MAC MCU + external managed switch.
Why the switch wins: KSZ8563 does L2/L3/L4 ACL in hardware — 16 entries/port, matching TCP/UDP src+dst port with mask. That offload collapses the MCU requirement from an HPM6750-class CPU down to a $3 Cortex-M4. It is the whole trick.
What would change the answer
Gigabit becomes a hard requirement → A4 (KSZ9563 swap, register-compatible) or B2 (HPM6750 + 2× RTL8211F).
Artery AVL rejected by a customer → A2 (STM32H723), pin-compatible-ish on the same footprint, +$9 BOM.
KSZ8563's 19-week lead time bites → the long pole of the whole BOM; B-family removes the switch IC entirely.
Cost pressure below $18 → A3 (CH32V317), cheapest proven silicon, but cert-hostile and LCSC-only.
Settled questions — don't re-litigate
No WCH chip has 2 Ethernet MACs. Not price, not toolchain — the silicon does not exist.
No dual-MAC STM32H7 exists. H723/H743/H745/H747/H753 all have exactly one MAC.
No USB-to-GbE bridge ASIC can run DHCP. LAN78xx / AX88179x / RTL815x are sealed; the "LAN7800 has a Cortex-M3" claim is false.
CDC-NCM + Microsoft OS 2.0 descriptors is the only driverless path across Win10+/macOS/Linux.
Compare all architectures
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Architecture
Verdict
Silicon
BOM @1K
Ethernet
Filtering
Hard reqs
Architecture detail
Click any card to expand: block diagram, full 14-requirement scoring, pros and cons.
The 14 PRD requirements
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Requirement
Weight
Why it matters
Chip reference
Component sourcing — live prices, stock, datasheets
Rejected — and why
These were investigated and ruled out. Recorded so the same ground isn't re-covered.