CH645 USB Hub+PD+Ethernet MCU
CH645 is a USB multi-host/multi-device RISC-V MCU/SoC from Nanjing Qinheng Microelectronics (WCH), based on the QingKe RISC-V4C core (up to 125 MHz). It integrates eight USB 2.0 high-speed PHYs and two USB PD/Type-C PHYs, supporting up to eight USB hosts and four USB devices; through four USB composite-device channels (including a 7-port HUB), it can scale to up to 28 USB devices. A 10/100M Ethernet MAC+PHY, SDIO, and multiple USART/I2C/SPI interfaces target PD HUBs, KVM, isolated/long-reach USB, and Type-C docks.
CH645W is a KVM-optimized variant for USB 2.0 high-speed 4-port KVM switches, integrating HUB, matrix switching, and composite devices without external HUB ICs or analog USB switches.
Core Specifications
| Item | Specification |
|---|---|
| Product type | USB multi-host/multi-device RISC-V MCU/SoC |
| Core | QingKe RISC-V4C; RV32IMCB; up to 125 MHz |
| Memory | 224 KB Flash + 28 KB Boot; RAM 72–80 KB |
| USB 2.0 HS | 8× HS PHY (CH645F: 5×); PDUSB 8 Host / 4 Device (CH645F: 5/1); up to 28 composite devices |
| USB composite/HUB | CH645W: 4-channel 4×HUB; CH645F: 1×HUB |
| USB extension/isolation | SerDes-based USB PHY for isolation and long-reach links |
| USB PD / Type-C | 2× PD controllers and PHY; PDUSB; Source / Sink / DRP |
| Ethernet | 10/100M MAC + integrated PHY |
| DMA | 11 general-purpose channels |
| Interfaces | 2× USART (LIN / ISO7816); 5× I2C (SMBus/PMBus); 2× SPI |
| Storage expansion | SDIO host/slave (eMMC / SD / SDIO cards) |
| Timers | Advanced, general-purpose, watchdog, system tick |
| GPIO | 40 (CH645W) / 13 (CH645F); some pins 5 V tolerant |
| Supply | 3.3 V or 3.3 V / 5 V (part/scenario dependent) |
| Packages | QFN68 (CH645W), QFN32 (CH645F) |
Part Comparison
| Item | CH645W | CH645F |
|---|---|---|
| Program + Boot area | 224K + 28K | 224K + 28K |
| RAM | 72–80K | 72–80K |
| GPIO | 40 | 13 |
| Advanced timers | 1 | 1 |
| General-purpose timers | 1 | 1 |
| Watchdog timers | 2 | 2 |
| USB PHY transceivers | 8 | 5 |
| USB isolated long-reach PHY | Yes | Yes |
| Built-in HUB composite USB device | 4-channel 4×HUB | 1×HUB |
| PDUSB: USB Host | 8 | 5 |
| PDUSB: USB Device | 4 | 1 |
| PDUSB: Type-C Source/Sink/DRP | 2 | 2 |
| Ethernet MAC+PHY | Yes | Yes |
| SDIO | 1 | 1 |
| USART | 2 | 2 |
| I2C | 5 | 4 |
| SPI | 2 | 1 |
| Package | QFN68 | QFN32 |
Summarized from the WCH official selection chart.
CH645W (KVM / high-density USB)
- Targets USB 2.0 HS 4-port KVM and multi-port PD HUBs: four composite channels + eight HS PHYs + on-chip USB matrix.
- Each composite channel: one HS 4-port HUB + three virtual sub-devices; up to 28 USB devices on one chip.
- No external HUB IC or analog USB switch; supports LS/FS/HS (1.5 / 12 / 480 Mbps).
- Button, keyboard/mouse hotkey, and IR switching; auto polling for monitoring with non-volatile settings.
CH645F (compact / streamlined USB)
- QFN32 package with fewer GPIO and USB resources vs CH645W.
- 1×HUB composite device, 5 USB PHYs, 5 Host / 1 Device; retains dual PD/Type-C and 100M Ethernet.
- Suited to smaller PD HUBs or USB gateways with fewer ports.
Block Diagram
The block diagram shows the 125 MHz RISC-V core, 224 KB Flash / 80 KB SRAM, PDUSB (USB 2.0 HS Host×8 / Device×28, PD×2 Type-C), 100M Ethernet, SDIO/USART/I2C/SPI, and timer/GPIO modules (image source: WCH official product page).
Key Features
- Single-chip USB HUB + PD + Ethernet reduces BOM for docks, KVM, and industrial USB gateways.
- CH645W pre-integrates KVM switching matrix vs multi-chip HUB + analog switch stacks.
- SerDes USB PHY supports isolation and long-reach USB.
- 224 KB Flash for Hub/PD/Ethernet stack and application firmware.
Typical Applications
- USB 2.0 HS 4-port KVM switches (keyboard/mouse pass-through, hotkeys, mixed devices)
- PD HUBs and Type-C docks (multi-port USB + fast charge + Ethernet)
- Isolated / long-reach USB extension and industrial USB aggregation
- Multi-USB composite gateways (with Ethernet / SDIO storage)
Design Notes
- Part selection: multi-port KVM / 4×HUB composite → CH645W; compact, fewer-port PD HUB → CH645F.
- Debug: SWD typically PA0 / PA1 (similar to CH570/CH572—confirm in manual).
- 28-device capability depends on four composite channels + HUB configuration—follow WCH SDK reference designs for descriptors and firmware.
- Confirm SDK/HDK availability and supply status with WCH; development via MounRiver Studio.
References
- WCH CH645 product page (Chinese)
- WCH CH645 product page (English)
- CH645W KVM solution notes (WCH via Sekorm)
- SoCXin/CH645 resources
- USB series
- Other model summary
Notes
This page is based on the WCH CH645 official product page, public selection manuals, and CH645W KVM application materials. Confirm Flash/SRAM partitioning, part differences, PD/Ethernet coexistence, and production support with the latest vendor documentation, SDK, and project validation.