CH343 - 6Mbps USB to Serial UART Chip | WCH
MPN: CH343 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.9 | $0.90 |
| 10 | $0.82 | $8.20 |
| 100 | $0.74 | $74.00 |
| 500 | $0.68 | $340.00 |
| 1,000 | $0.62 | $620.00 |
CH343 Overview
A USB-to-UART bridge is a type of interface converter IC in the broader USB controller hierarchy: it enumerates as a USB communications device on the host and exposes a standard COM port, allowing legacy serial peripherals, MCUs, and programmers to connect to modern computers that no longer provide RS-232 ports. Bridges like the CH343 sit between USB physical-layer controllers and UART protocol devices in the system chain.
Key features include 6 Mbps maximum baud rate (significantly faster than the 1-2 Mbps of typical competitors such as CH340 or CP2102), serial signal levels configurable for 5V, 3.3V, 2.5V, or 1.8V logic via the VIO supply, an integrated crystal oscillator that removes the need for an external crystal, and common MODEM handshake signals for hardware flow control.
Architecturally, the CH343 contains a USB full-speed transceiver, an integrated USB protocol engine, and built-in firmware that emulates a standard asynchronous serial interface. On Windows, the chip works with the operating-system built-in CDC class driver or the vendor high-speed VCP driver, so most existing serial applications run without modification. Dual-supply operation allows VBUS powering of the chip while the MCU side runs from an independent 5V, 3.3V, 2.5V, or 1.8V rail.
Typical applications include MCU programming and debugging adapters, embedded development boards (the chip is used on ESP32-class and Waveshare USB-UART boards), industrial equipment serial-port upgrades, and point-of-sale or instrumentation links.
Design consideration: connect the CFG pin appropriately to select CDC or VCP behavior, and keep the VIO level matched to the target MCU to avoid level-shifting damage; RXD/TXD are the only mandatory cross-connections in simple links.
This page synthesizes distributor pricing, drop-in family alternatives, and practical design notes not found in the manufacturer datasheet, with data verified as of 2026-10-20.
Drop-in alternatives for CH343 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
CH343G
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
CH343P
✅ Drop-In📋 Reference alternative (not in catalog)
CH343C
✅ Drop-In📋 Reference alternative (not in catalog)
CH343 Specifications
| Function | USB to high-speed asynchronous serial UART converter |
| Maximum Baud Rate | 6 Mbps |
| Baud Rate Adaptation | Automatic identification, 115200 bps and below |
| VIO Logic Levels | 5 V / 3.3 V / 2.5 V / 1.8 V |
| Supply Voltage (VCC) | 3.3 V / 5 V |
| USB Interface | USB 2.0 full-speed |
| Integrated Crystal Oscillator | Yes (no external crystal required) |
| MODEM Signals | Common MODEM handshake signals supported |
| Driver Support | OS built-in CDC driver or vendor high-speed VCP driver |
| Operating Temperature | -40C to +85C |
| Package (CH343G variant) | SOP-16 |
| Mounting Type | Surface Mount |
| Applications | Serial port expansion, MCU-to-USB upgrade |
| Power Modes | Single supply (VBUS) or dual power supply mode |
| Typical Unit Price | 0.7342 USD (LCSC, as of 2026-10-20) |
| RoHS Status | Compliant |
CH343 sop-16 Pin Configuration Guide
Pin configuration for CH343 (sop-16 package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for CH343.
Refer to the datasheet for full pin configuration.
Typical Applications
CH343 is suitable for 6 applications: MCU Programming and Debugging Adapters, Embedded Development Boards, Industrial Equipment Serial Port Upgrade, USB-to-UART Adapter Cables and Dongles, Point-of-Sale and Instrumentation Links, IoT Gateways and Smart Home Hubs.
MCU Programming and Debugging Adapters
The CH343 is a natural fit for USB-to-TTL programming adapters for ESP32, ESP8266, and STM32 bootloaders because its 6 Mbps maximum baud rate cuts firmware download time versus 2 Mbps-class bridges, and its VIO pin accepts 3.3V, 1.8V, 2.5V, or 5V to match the target logic directly without level shifters. In a typical adapter, the chip enumerates via the OS CDC driver or the WCH VCP driver, and the RTS/DTR MODEM signals drive the MCU auto-reset and boot-mode strapping circuits, enabling one-button flashing. Because the crystal is integrated, the adapter PCB needs only decoupling capacitors and the USB connector, keeping adapter cost near the chip price of roughly $0.74. Boards like the Waveshare CH343 USB UART Board demonstrate this exact topology.
Recommended
Embedded Development Boards
Development and evaluation boards benefit from the CH343 as the on-board USB-to-serial bridge because it removes the external crystal (built-in oscillator saves layout area), supports dual power supply mode so the MCU can run from its own 3.3V, 2.5V, or 1.8V rail while VBUS powers the bridge, and offers hardware flow control for bootloaders or logs that need CTS/RTS. The 6 Mbps capability is valuable when streaming high-rate sensor logs or trace output that would saturate a 115200 bps legacy bridge. Per the WCH datasheet, only RXD and TXD are mandatory cross-connections in minimal designs, so a two-wire serial console costs almost nothing to add. Boards such as Waveshare modules use CH343 in exactly this role.
Recommended
Industrial Equipment Serial Port Upgrade
Legacy industrial devices - PLC panels, meters, CNC accessories - often expose only RS-232/TTL serial ports, while service laptops ship without any COM ports. The CH343 bridges this gap: it enumerates as a standard CDC serial port on Windows, macOS, and Linux, so existing commissioning software runs unmodified, as noted in the WCH datasheet. Its -40C to +85C operating range covers industrial cabinet temperatures, and the automatic baud-rate adaptation (115200 bps and below) tolerates devices configured at non-standard legacy rates. In dual-supply mode the chip draws power from USB VBUS while the equipment-side logic stays on its own 5V or 3.3V rail, isolating grounds cleanly. The MODEM handshake signals support equipment requiring hardware flow control.
Recommended
USB-to-UART Adapter Cables and Dongles
Consumer and maker USB-to-TTL dongles are the highest-volume application for the CH343 family. The chip's integrated crystal eliminates the single most failure-prone external passive of older CH340G designs, its 6 Mbps ceiling supports fast serial flashing tools, and CDC class-driver operation means end users plug the dongle into Windows 10/11, macOS, or Linux with zero driver installation. The VIO flexibility (5V/3.3V/2.5V/1.8V, selectable by tying the VIO pin) lets one dongle PCB serve multiple logic families by populating a jumper. At roughly $0.74 unit cost from LCSC as of 2026-10-20, total dongle BOM stays well under one dollar, undercutting CP2102- or FT232-based designs by several multiples while exceeding their speed.
Recommended
Point-of-Sale and Instrumentation Links
POS terminals, barcode scanners, lab instruments, and medical accessories frequently communicate over asynchronous serial at moderate rates. The CH343 suits these products because the WCH vendor VCP driver exposes configurable latency and buffering for reliable transaction throughput, the built-in firmware emulates a standard UART so application software is untouched, and the CDC mode simplifies certification on modern OS versions. Per the datasheet, common MODEM signals support peripherals with hardware handshake requirements, and the 6 Mbps ceiling accommodates high-speed receipt or data-logging traffic. Dual-supply operation lets the peripheral run from its own isolated 3.3V or 5V rail while the host side is bus-powered - useful for meeting safety isolation practices in instrumentation enclosures.
Recommended
IoT Gateways and Smart Home Hubs
IoT gateways often use a USB-connected serial console for module management, Zigbee/Thread co-processor flashing, or cellular modem AT-command channels. The CH343 fits these roles with its 6 Mbps throughput (sufficient for modem AT streams and co-processor image downloads), 1.8V VIO support matching modern low-voltage co-processors, and -40C to +85C rating for unconditioned enclosures. Because Linux enumerates the chip via the built-in CDC driver, no kernel module maintenance is needed across OS updates - a real operational benefit for fleet-deployed gateways. Waveshare's CH343 USB UART Board documentation shows CFG-pin configuration for CDC mode, which is the recommended setting for headless Linux hosts using software flow control by default.
Recommended
Recommended Products Summary
Engineering reference data for CH343 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CH343G | CH343P | CH343C | FT232RL |
|---|---|---|---|---|---|
| Package | SOP-16 (CH343G) | SOP-16 | SOP-16 | SOP-16 | SSOP-28 (not pin-compatible) |
| Brand | WCH | WCH | WCH | WCH | FTDI |
| Max Baud Rate | 6 Mbps | 6 Mbps | 6 Mbps | 6 Mbps | 3 Mbps |
| VIO Logic Levels | 5V / 3.3V / 2.5V / 1.8V | 5V / 3.3V / 2.5V / 1.8V | 5V / 3.3V / 2.5V / 1.8V | 5V / 3.3V / 2.5V / 1.8V | 5V / 3.3V only |
| Integrated Crystal | Yes | Yes | Yes | Yes | Yes |
| Typical Unit Price | $0.74 (LCSC, 2026-10-20) | $0.7342 (LCSC) | $0.90 - $1.20 (est.) | $0.80 - $1.00 (est.) | $3 - $5 (est.) |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| Driver Support | CDC built-in + WCH VCP | CDC built-in + WCH VCP | CDC built-in + WCH VCP | CDC built-in + WCH VCP | FTDI VCP/D2XX (mature ecosystem) |
Key Differentiators
- Highest baud rate in cost class (vs FT232RL)
- Ultra-low-voltage logic support (vs CP2102)
- No external crystal required (vs CH340G)
Design Notes
In dual power supply mode, power the CH343 from USB VBUS and feed VIO from the target MCU's own self-powered rail (5V, 3.3V, 2.5V, or 1.8V per the WCH datasheet). Never let VIO float or exceed the MCU rail, or the RXD/TXD drivers can overdrive the target. Place 0.1uF decoupling on VCC and VIO close to the pins; excepting RXD and TXD, other signal pins are optional connections in minimal designs.
The CFG pin determines CDC vs VCP behavior: the Waveshare CH343 USB UART Board documentation notes that boards default to software flow control, and hardware flow control requires connecting CFG to EN for CDC mode, then enabling flow control in the host application for VCP mode. If your adapter appears to enumerate but data will not flow, check CFG first. Also confirm the suffix (G/K/P/C) pin map in CH343DS1 before layout, since assignments differ between package variants.
Because the crystal is built in, keep the USB D+/D- pair routed as a matched 90-ohm differential pair no longer than necessary, and reserve test points on TXD/RXD for bring-up. For auto-reset flashing circuits, route DTR/RTS through a pair of small-signal transistors (classic RTS/DTR cross-coupling) to the target EN/BOOT pins, matching ESP32 reference designs.
Compliance Information
RoHS compliance stated on LCSC product listing for CH343G; other compliance attributes not stated in provided data.
