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USB 3.2 Type-C 转 10G SFP+ network card project is starting

05/25/2026

Realtek RTL8159 USB 3.2 Type-C to 10G SFP+ Project Evaluation

Project Evaluation / PROTOTYPE

USB 3.2 Type-C to 10G SFP+ Project
Realtek RTL8159 + 10G PHY Adapter Solution

Provides a low-cost, non-disassembled, plug-and-play SFP+ adapter solution for laptops / mini PCs / edge gateways without PCIe slots or 10G ports, connecting to data center SFP+ fiber links

StatusProject Evaluation Product FormUSB 3.2 Type-C to 1×SFP+ 10GbE ChipRealtek RTL8159 10GbE USB + 10G PHY

Key Point: When edge devices like laptops/NUCs have no PCIe slots and no 10G ports, but need to connect to data center SFP+ fiber links, traditional PCIe NICs cannot be used. This project is based on Realtek RTL8159 (10GbE USB 3.2 Gen 2×2 chip released at Computex 2025) paired with 10G PHY/SFP+ cage to build a compact USB-C to 10G SFP+ adapter. With just one USB 3.2 Type-C port, it can access 10G fiber networks via SFP+ optical modules, providing a plug-and-play solution for mobile office and edge O&M.

1. Product Structure

The diagram shows the functional structure of the USB-C to 10G SFP+ adapter. RTL8159 acts as the 10GbE USB controller, connecting upstream to the host via USB 3.2 Type-C (Gen 2×2, 20Gbps). Internally, it is paired with a 10G PHY and SFP+ cage to insert SFP+ optical modules. Power (LDO/Buck), EEPROM/Flash, and LED indicators follow the reference system design.

Figure 1: Product structure USB-C ↔ RTL8159 ↔ 10G PHY/SFP+ cage ↔ Fiber

2. RTL8159 + 10G PHY Actual Specifications

Controller Chip	Realtek RTL8159 10GbE USB controller, released at Computex 2025, 28nm process, built-in ARM Cortex-M4 core, QFN68 8×8mm package
Upstream Interface	USB 3.2 Type-C, Gen 2×2 20Gbps bidirectional bandwidth, backward compatible with USB 3.2 Gen2/Gen1, USB 2.0
Downstream Port	1× SFP+ cage, supports SFP+ optical modules, 10GbE fiber access, LC duplex interface
Rate Negotiation	10G / 5G / 2.5G / 1G / 100M auto-negotiation, SFP+ module automatic link protocol adaptation
PHY / Optical Module	Built-in 10G PHY + SFP+ cage, supports 10GBASE-SR/LR/CR and other SFP+ optical modules/copper cables (specific module models subject to compatibility)
Interrupt / Checksum	RSS hardware queues, IPv4/IPv6/TCP/UDP checksum offload, interrupt coalescing, ARP&NS protocol interrupt, MAC address filtering
Jumbo Frame / Power	Supports 16KB jumbo frames, EEE 802.3az energy saving mode, link power auto-sleep
Wake / Boot	Supports Wake-on-LAN (WoL), RealWoW™ remote wake-up (optional), CDC-ECM / CDC-NCM device class, UEFI PXE boot
QoS / VLAN	IEEE 802.1p QoS, IEEE 802.1q VLAN tagging, 802.3x flow control
Power / Consumption	Bus-powered, total power consumption approx. 1.95W (RTL8159 core)
System Support	Windows 10/11 64bit, Linux kernel 5.8+ r8152 driver, macOS (subject to Realtek official driver)
Size / Form	Adapter form, USB-C conversion, operating temperature 0°C~55°C

Note: RTL8159 is a USB to 10GbE controller, originally designed mostly for RJ45 ports. This project expands to fiber (SFP+) form via 10G PHY + SFP+ cage. The project is modified from RTL8159's RJ45 reference design. 10G upstream bandwidth is provided by USB 3.2 Gen 2×2 20Gbps Type-C interface. Gen2×1 (10Gbps) actual test approx. 6.6~7.4Gbps, Gen1 (5Gbps) actual test approx. 3.5~4.7Gbps, affected by USB protocol overhead.

3. Protocol Function Layered Architecture

The core value of RTL8159 is offloading protocol processing from the CPU. The diagram below shows the project interrupt/protocol function layered architecture.

Figure 2: Architecture from SFP+ hardware to application layer, protocol checksum/interrupt handled by RTL8159 hardware

4. Current Status (Evaluation)

✅ Chip selection / BOM confirmed: RTL8159 + 10G PHY + SFP+ cage ✅ Schematic V1: USB-C interface / PHY and SFP+ cage connection / EEPROM / LED / power design 🔄 PCB Layout review: 4-layer board, USB signal integrity, SFP+ high-frequency signal impedance, EMI optimization 🔜 Board test: USB 20Gbps link stability / SFP+ module recognition / 10G fiber throughput / jumbo frame / WoL 🔜 Driver verification: Windows 11 / Linux (r8152) / macOS actual test

5. Target Application Scenarios

Laptop / Mini PC / Portable O&M: Devices without PCIe slots can access 10G fiber networks via USB-C port
NUC / ARM Edge Devices: Small fanless devices can expand 10G fiber port without disassembly
Edge Computing / Portable Capture: Engineers can carry a laptop + adapter to connect to SFP+ fiber links for packet capture/analysis
Temporary Expansion: Provide 10G fiber access for USB-C workstations/servers

Editor note: RTL8159 is an entry-level "USB to 10G" solution. This project transforms from RJ45 form to SFP+ fiber form, filling the portable market gap of "USB-C to 10G fiber". Note: 10G upstream is provided by USB 3.2 Gen 2×2 20Gbps Type-C interface. Current interface mode of Apple Silicon Mac / some laptops is approx. 5.5~6.3Gbps. The product is positioned for portable access, not full-speed server applications, no hardware pre-bias.