WCH's CH398 combines a 5 Gbps USB 3.0 PHY with a full Gigabit Ethernet MAC+PHY in a single chip, offering a compact and cost-effective USB-to-Ethernet adapter solution compatible with mainstream operating systems.
The CH398 was listed on the WCH homepage as a recent product release and has been discussed in the technical community as a significant addition to WCH's growing lineup of interface and connectivity chips.
| Feature | Specification |
|---|---|
| USB Interface | USB 3.2 Gen1 (5 Gbps SuperSpeed) |
| Ethernet | 10/100/1000 Mbps Gigabit |
| Integration | USB PHY + Ethernet MAC + Ethernet PHY (single chip) |
| OS Support | Windows, Linux, macOS (mainstream OS) |
| Application | USB-to-Gigabit-Ethernet adapter |
WCH has been building a comprehensive connectivity chip portfolio that spans USB, Ethernet, and wireless interfaces. The CH398 sits at the intersection of USB and Ethernet -- two of the most ubiquitous wired communication standards.
| Chip | Interface | Speed | Integration |
|---|---|---|---|
| CH398 | USB 3.0 | 1000 Mbps | USB PHY + ETH MAC + ETH PHY |
| CH390 | Parallel/SPI | 10/100 Mbps | ETH MAC + PHY (low power) |
| CH394 | Parallel/SPI | 10/100 Mbps | ETH MAC + PHY + TCP/IP stack |
| CH182 | MII/RMII | 10/100 Mbps | ETH PHY only |
| CH32V307 (MCU) | Built-in | 1000M MAC + 10M PHY | RISC-V MCU + Ethernet |
| CH32H417 (MCU) | Built-in | 100M PHY | RISC-V dual-core + USB 3.0 + Ethernet |
The primary use case is USB-to-Gigabit-Ethernet adapters. With USB 3.0's 5 Gbps bandwidth, the CH398 can sustain full Gigabit Ethernet throughput without the bottleneck that affects USB 2.0-based solutions (which are limited to 480 Mbps theoretical, ~400 Mbps practical).
For RISC-V SBCs like those based on the SpacemiT K1 (which already features dual RGMII with YT9152S for 8-port physical isolation), the CH398 offers a way to add additional network interfaces via USB without redesigning the PCB. This is particularly useful for:
The CH398 pairs naturally with WCH's USB hub chips:
| Hub Chip | Ports | Features |
|---|---|---|
| CH637 | 7x USB 3.2 Gen1 + 3x PD PHY | Type-C, PDHUB, 100W fast charge |
| CH339 | 7x USB HUB + 100M ETH + SD reader + PD + JTAG/UART/SPI/I2C | Multi-function |
A CH637 USB 3.0 hub with a CH398 on one downstream port creates a multi-function dock: USB port expansion plus Gigabit Ethernet, all from a single USB 3.0 upstream connection.
The USB-to-Gigabit-Ethernet chip market has been dominated by a few players:
| Solution | USB Version | Ethernet | Notes |
|---|---|---|---|
| WCH CH398 | USB 3.0 (5 Gbps) | Gigabit | New entrant, single-chip integration |
| ASIX AX88179 | USB 3.0 | Gigabit | Market incumbent, widely supported |
| Realtek RTL8153 | USB 3.0 | Gigabit | Common in consumer adapters |
| Microchip LAN7800 | USB 3.0 | Gigabit | Industrial focus |
WCH's advantage lies in its typical pricing strategy -- WCH chips are known for aggressive pricing (the CH32V003 MCU at $0.1 disrupted the MCU market). If the CH398 follows this pattern, it could offer a cost-competitive alternative in the USB Ethernet adapter space.
While the CH398 itself is a bridge chip (not a RISC-V MCU), it complements WCH's RISC-V MCU ecosystem. In a complete network appliance design:
This stack represents a fully RISC-V-based network infrastructure, from the $0.1 control MCU to the multi-core AI processor.
WCH typically provides drivers for Windows, Linux, and macOS. For Linux-based systems (including OpenWrt), the CH398 would likely use a CDC-ECM or vendor-specific USB network driver. Developers should check the WCH website for driver availability and kernel version compatibility.
For OpenWrt-based routers (a common use case for RISC-V gateways like the SpacemiT K1 platform), having a USB-pluggable Gigabit Ethernet option means network port count can be expanded without hardware redesign -- simply plug in a CH398-based adapter.