Adom molecule · board

USB3.0 → Ethernet Molecule

A self-contained USB-C to Gigabit Ethernet data-only adapter built around the Microchip LAN7800. This page bundles the complete KiCad library and links all 28 components as their own wiki pages.

MPN USB3toEthernetDataOnly_Molecule Mfr Adom Board 40 × 40 mm · 4-layer Parts 54 placed · 0 DNP Source KiCad 10

At a glance

Host interface

USB 3.0 (5 Gbps) · USB Type-C

Network

10 / 100 / 1000 BASE-T Gigabit Ethernet

Controller

Microchip LAN7800-I/Y9X (QFN-48)

SS orientation mux

TI HD3SS3212 (2:1)

Power

USB bus-powered · NCP1117 3.3 V LDO

Config

M93C66 EEPROM · 25 MHz crystal

Form factor

40 × 40 mm · 4-layer · 1.6 mm

Mounting

4 × press-fit machine-pin standoffs

How the board works

USB-C input

A USB Type-C receptacle (J2) with the HD3SS3212 SuperSpeed 2:1 mux (U5) so the USB 3.0 pair routes correctly whichever way the cable is plugged. A TL331LV comparator (U2), chosen for its reversed input pinout so the orientation decision comes out the right way round, plus CC resistors present the board as a bus-powered USB device.

3.3 V power

A fixed NCP1117-3.3 LDO (U3, SOT-223) drops USB VBUS (5 V) to the 3.3 V rail that feeds the controller, with local decoupling (C1, C2).

LAN7800 core

The Microchip LAN7800 (U1, QFN-48) is a single-chip USB 3.0 → Gigabit Ethernet controller integrating the USB device, MAC and 10/100/1000 PHY. An M93C66 EEPROM (U4) stores MAC/config and a 25 MHz crystal (Y1) provides the reference; ferrite beads (FB1–FB3) and L4 clean the supplies.

RJ45 / magnetics

An HC-RJ45-511Q jack with integrated magnetics (J3) carries the four Gigabit twisted pairs to the outside world and drives the built-in link / activity LEDs. R1/R2/R6 handle termination.

LEDs & mounting

Two status LEDs (D1 blue, D2 red), four machine-pin standoffs (MP1–MP4) that let the molecule seat into a carrier, and seven test points (TP1–TP7) for bring-up.

Board maps

Top · F.Cu

Bottom · B.Cu

USB-C input 3.3 V power LAN7800 core RJ45 / magnetics LEDs & mounting

Bill of materials · 54 parts

Qty	Value	Footprint	Designators · section
7×	TestPoint	TestPoint_Pad_D1.0mm	TP1, TP2, TP3, TP4, TP5, TP6, TP7
4×	C_10uF_0402	C_0402_1005Metric	C1, C2, C6, C50
4×	~	MachinePinLargeShort	MP1, MP2, MP3, MP4
3×	BLM15AG601SN1D	R_0402_1005Metric	FB1, FB2, FB3
3×	C_100nF_0402	C_0402_1005Metric	C3, C4, C7
3×	R_5.1K_0402	R_0402_1005Metric	R3, R5, R9
2×	C_100nF_16V_0402	C_0402_1005Metric	C10, C11
2×	C_10nF_0402	C_0402_1005Metric	C8, C9
2×	C_18pF_0402	C_0402_1005Metric	C47, C48
2×	C_1uF_0402	C_0402_1005Metric	C46, C49
2×	R_300R_0402	R_0402_1005Metric	R1, R2
1×	C_10uF_0603	C_0603_1608Metric	C5
1×	HC-RJ45-511Q-1-2	RJ45-SMD_HC-RJ45-511Q-1-2	J3
1×	HD3SS3212IRKSR	DHVQFN-20_L4.5-W2.5-P0.50-BL-EP	U5
1×	LAN7800-I/Y9X	QFN-48_L7.0-W7.0-P0.50-BL-EP5.3	U1
1×	LED_BLUE_0603	LED_0603_1608Metric	D1
1×	LED_RED_0603	LED_0603_1608Metric	D2
1×	TL331LV	TL331LV	U2
1×	LOGO2	Adom Logo Size 2	LOGO2
1×	L_3.3uH_1.81A_104mR_3x3	L_Wurth_WE-LQSH-3012	L4
1×	M93C66	SOIC-8_3.9x4.9mm_P1.27mm	U4
1×	NCP1117-3.3_SOT223	SOT-223-3_TabPin2	U3
1×	R_12K_0402	R_0402_1005Metric	R41
1×	R_1M_0402	R_0402_1005Metric	R6
1×	R_2.2K_0402	R_0402_1005Metric	R8
1×	R_2K_0402	R_0402_1005Metric	R39
1×	R_4.3K_0402	R_0402_1005Metric	R4
1×	R_7.68k_0402	R_0402_1005Metric	R7
1×	SKRPACE010	SKRPACE010	SW1
1×	USB4115-03-C	USB-C-SMD_U263-241N-4BQC04	J2
1×	X322525MOB4SI	Crystal_SMD_3225-4Pin_3.2x2.5mm	Y1

Linked components · 28

The board depends on its 28 components; each is its own wiki component page (symbol + footprint + 3D + adom-lbr JSON).

Bundled KiCad library

This page ships the complete, self-contained KiCad library for the board: 29 symbols, 16 footprints, 15 3D models (STEP + GLB), all linked.

USB3toEthernetDataOnly.kicad_sym          all 29 schematic symbols
USB3toEthernetDataOnly.pretty/            16 footprints
USB3toEthernetDataOnly.3dshapes/          15 STEP + GLB models

Install

# 1. download & extract, e.g. ~/Documents/KiCAD/USB3toEthernetDataOnly/
# 2. Preferences → Configure Paths → add:
#      USB3TOETH_3D = <extract-dir>/USB3toEthernetDataOnly.3dshapes
# 3. add to sym-lib-table / fp-lib-table:
(lib (name "USB3toEthernetDataOnly")(type "KiCad")(uri "<dir>/USB3toEthernetDataOnly.kicad_sym"))
(lib (name "USB3toEthernetDataOnly")(type "KiCad")(uri "<dir>/USB3toEthernetDataOnly.pretty"))

Downloads

board .kicad_pcb schematic .kicad_sch symbols .kicad_sym board .glb (3D) viewer source

How this page was built · what is & isn't verified

Generatedfrom the design files

The 3D model, the bill of materials (grouped by value + footprint, designators listed), the board maps, the functional-section membership and the part counts are all derived mechanically from the .kicad_pcb / .kicad_sch in this repo — they cannot drift from the design. Sections come straight from the schematic sheets (USB, Power, Data, Ethernet). No part is marked do-not-populate in this design (0 DNP).

Generated3D coverage

The interactive model shows 46 of 54 footprints as solid bodies. The 37 stock parts were placed by the KiCad 10 STEP exporter; the 9 custom parts (J2 USB-C, J3 RJ45, SW1, MP1–MP4, U1 LAN7800, U5 HD3SS3212) were positioned with a transform calibrated to 0.0 mm against ground-truth stock parts. The remaining 8 footprints have no 3D body by design — they are test pads and a logo (TP7, TP6, TP4, LOGO2, TP3, TP2, TP5, TP1). A few library models carry a baked-in "LCEDA / EasyEDA" mark from their source STEP; that is cosmetic and does not affect geometry.

Author-asserteddesign intent

The section descriptions and how-it-works narrative are the board author's account of how the design is meant to function — true because the author says so, not because a file proves it.

Not verified hereper-part datasheet values

Part values shown are as drawn in the schematic, not re-verified against each component's own datasheet — that is what the individual component pages (linked above) are for.