CH340C - USB to UART Bridge IC, SOP-16 | WCH (Qinheng Micro)
MPN: CH340C ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.55 | $0.55 |
| 10 | $0.49 | $4.90 |
| 100 | $0.43 | $43.00 |
| 500 | $0.4 | $200.00 |
| 1,000 | $0.3725 | $372.50 |
| 3,000 | $0.34 | $1,020.00 |
CH340C Overview
A USB-to-UART bridge (also called a USB-to-serial converter) is a type of interface IC that bridges a USB host (computer) to a UART peripheral (microcontroller, GPS module, legacy serial device). The hierarchy is: USB bridge > USB-to-UART bridge > serial interface IC > interface controller > integrated circuit. The bridge enumerates as a Virtual COM Port (VCP) on the host OS, so existing PC software treats the USB cable as a legacy COM port without code changes.
Key features include on-chip 12 MHz oscillator (no crystal required), 3.3 V and 5 V operating modes selectable via the V3 pin, USB 2.0 full-speed (12 Mbps) compliance, integrated USB termination and pull-up resistors, and built-in power-on reset. Maximum baud rate is 2 Mbps per the WCH datasheet, covering most MCU debug and firmware-flashing workloads.
The CH340C uses a CMOS process with an internal SIE (Serial Interface Engine), endpoint FIFO buffer, and UART block. Suspend current is rated at approximately 50 uA per the WCH data, and active supply current is typically 7 mA during full-speed USB traffic - well within bus-powered budgets.
Typical applications include Arduino clone boards, ESP-01/NodeMCU programmers, USB-to-TTL debug cables, and industrial serial port expansion where the host PC has dropped native RS-232 ports. The 5 V tolerance also lets the bridge interface legacy 5 V MCUs directly.
When designing with the CH340C, route the USB D+/D- pair as a 90-ohm differential pair with a common-mode choke, place the V3-decoupling capacitor close to the pin, and confirm host-OS driver availability - native Windows 10/11 and Linux/macOS support exists, but some legacy Windows installations require the WCH-supplied INF driver.
This page synthesizes distributor pricing, verified pin-compatible drop-in variants (CH340B, CH340N, CH340E) in the same SOP footprint family, and practical PCB/design notes not collected in a single spot in the WCH datasheet.
Drop-in alternatives for CH340C — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with CH340C (same form factor and footprint) — differing in Manufacturer, Operating Temperature, Package, Driver Support, Product Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
CH340B
✅ Drop-In📋 Reference alternative (not in catalog)
CH340E
✅ Drop-In📋 Reference alternative (not in catalog)
CH340C Specifications
| Product Type | USB to UART Bridge Controller IC |
| USB Standard | USB 2.0 Full-Speed (12 Mbps) |
| Supply Voltage | 3.3 V or 5 V (mode selected by V3 pin) |
| Operating Temperature | -20 C to +70 C |
| Maximum Baud Rate | 2 Mbps |
| Suspend Current | 50 uA (typical) |
| Active Supply Current | 7 mA (typical, full-speed traffic) |
| On-Chip Oscillator | Yes - 12 MHz internal (no external crystal required) |
| UART Signals | TXD, RXD, RTS, CTS, DTR, DSR, DCD, RI |
| Package | SOP-16 |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Driver Support | Windows 7/8/10/11, Linux (kernel CDC-ACM), macOS |
| Manufacturer | Nanjing Qinheng Microelectronics Co., Ltd. (WCH) |
CH340C Pin Configuration
| Pin 1 | GND — Ground reference |
| Pin 2 | TXD — UART transmit output to host MCU |
| Pin 3 | RXD — UART receive input from host MCU |
| Pin 4 | V3 — 3.3 V/5 V mode select (tie to VCC for 5 V, tie to 3V3 for 3.3 V) |
| Pin 5 | UD+ — USB D+ data line (differential pair with UD-) |
| Pin 6 | UD- — USB D- data line (differential pair with UD+) |
| Pin 7 | GND — Ground (USB shield tie point) |
| Pin 8 | XI — Crystal input (NC on CH340C - internal oscillator used) |
| Pin 9 | XO — Crystal output (NC on CH340C - internal oscillator used) |
| Pin 10 | CTS — Clear-to-send MODEM input (active low) |
| Pin 11 | RTS — Request-to-send MODEM output (active low) |
| Pin 12 | DTR — Data-terminal-ready MODEM output (active low; used for auto-reset) |
| Pin 13 | RI — Ring indicator MODEM input (active low) |
| Pin 14 | DCD — Data-carrier-detect MODEM input (active low) |
| Pin 15 | DSR — Data-set-ready MODEM input (active low) |
| Pin 16 | VCC — Supply voltage (3.3 V or 5 V per V3 pin) |
Typical Applications
CH340C is suitable for 6 applications: Arduino Uno/Nano Clone USB-UART Bridge, ESP8266/ESP32 USB Programmer Board, USB-to-TTL Serial Debug Cable, Industrial Serial Port Expansion Card, IoT Sensor Node USB Configuration Port, Educational Electronics Trainer Board.
Arduino Uno/Nano Clone USB-UART Bridge
The CH340C's on-chip 12 MHz oscillator eliminates the external crystal the legacy CH340G required, reducing BOM count by 3 components and saving roughly 20 mm^2 of PCB area - critical for the Arduino Nano form factor. Its 5 V UART tolerance lets it drive the ATmega328P's RX/TX lines directly without level shifters, and the WCH CH341SER driver achieves plug-and-play enumeration as a Virtual COM Port on Windows 10/11 and Linux/macOS without firmware changes. Placed between the USB micro-B connector and the MCU reset/auto-reset DTR capacitor, it delivers the same serial debug experience as the original FTDI-based Arduino Uno at one-fifth the cost. Best fit when BOM cost dominates over driver signature stability.
Recommended
ESP8266/ESP32 USB Programmer Board
The CH340C powers NodeMCU, Wemos D1 mini, and generic ESP-01 programmer boards where its 3.3 V UART mode (V3 pin tied to 3V3) provides the correct logic level for the ESP8266's 3.3 V GPIO. At 2 Mbps maximum baud rate per the WCH datasheet, it handles the ESP8266's default 74880 bps bootloader and the 921600 bps high-speed flash mode without flow-control bottlenecks. The 50 uA suspend current and 7 mA active current keep total board draw within USB bus-powered limits. Placed adjacent to the USB micro-B connector with a 0.1 uF decoupling cap on VCC, it provides reliable auto-programming on reset. Best fit when the design targets 3.3 V MCUs and tight cost budgets.
Recommended
USB-to-TTL Serial Debug Cable
The CH340C enables sub-$1 USB-to-TTL debug cables used by engineers to log UART output from 3.3 V or 5 V MCUs. Its SOP-16 package fits inside a standard USB-A stick enclosure, and the integrated 12 MHz oscillator eliminates the 2 capacitors plus crystal required by the CH340G - shrinking the BOM to 1 IC, 1 ferrite bead on USB VBUS, 2 decoupling caps, and a USB connector. The full MODEM signals (RTS/CTS/DTR/DSR/DCD/RI) are exposed on a 6-pin header, supporting hardware flow control with MCUs that demand it. Best fit for field-engineering debug tools where cost and size outweigh industrial-grade driver requirements.
Recommended
Industrial Serial Port Expansion Card
The CH340C adds USB-derived COM ports to industrial PCs that have dropped native RS-232 headers. Its -20 C to +70 C industrial operating range per the WCH datasheet covers most factory-floor enclosures, and 5 V tolerance lets it drive legacy 5 V sensor UARTs directly. Multiple CH340Cs on a single USB hub can enumerate as COM3, COM4, COM5... simultaneously for parallel data acquisition from PLCs or sensors. Best fit when adding isolated, low-cost serial ports to legacy industrial PCs without opening the chassis. Caution: verify WCH driver support on air-gapped industrial Windows builds before deployment.
Recommended
IoT Sensor Node USB Configuration Port
The CH340C serves as the configuration UART on battery-powered IoT sensor nodes that connect to a USB host only for provisioning. Its 50 uA suspend current per the WCH datasheet is negligible against typical node sleep currents (10-100 uA), and the 7 mA active current is only drawn during the brief configuration window. The on-chip oscillator saves space in ultra-compact sensor PCB designs. Placed with its V3 pin tied to the node's 3.3 V rail, it provides a debug console without disturbing the main MCU's firmware. Best fit for battery-powered IoT nodes that need USB provisioning but cannot afford the BOM cost of an FTDI.
Recommended
Educational Electronics Trainer Board
The CH340C is the standard USB-serial bridge on educational trainer boards for microcontrollers, robotics, and embedded systems courses where cost determines classroom adoption. The WCH CH341SER driver's broad Windows/Linux/macOS support avoids IT-department driver-signing friction in school computer labs, and the chip's $0.37 unit cost at 1k quantity keeps total trainer-board BOM under $5. Its 5 V tolerance matches the Arduino/Raspberry Pi Pico educational ecosystem. Best fit for K-12 and university electronics labs where hundreds of boards must be affordable and plug-and-play across mixed-OS computer fleets.
Recommended
Recommended Products Summary
Engineering reference data for CH340C — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CH340B | CH340E | CH340N |
|---|---|---|---|---|
| Package | SOP-16 | SOP-16 - same | SOP-16 - same | SOP-8 - smaller (cross-package) |
| Brand | WCH (Qinheng Micro) | WCH (same brand) | WCH (same brand) | WCH (same brand) |
| External Crystal Required | No (internal 12 MHz) | Optional | No (internal) | No (internal) |
| Operating Voltage | 3.3 V or 5 V (V3 pin) | 3.3 V or 5 V | 5 V only | 3.3 V or 5 V |
| USB Standard | USB 2.0 Full-Speed (12 Mbps) | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed |
| Maximum Baud Rate | 2 Mbps | 2 Mbps | 2 Mbps | 2 Mbps |
| MODEM Signals | Full set (RTS/CTS/DTR/DSR/DCD/RI) | Full set | Full set | Reduced (TX/RX/RTS/CTS only) |
| Unit Price (qty 1000) | $0.37 | $0.38 | $0.36 | $0.30 |
Key Differentiators
- Integrated 12 MHz oscillator eliminates external crystal (vs CH340G)
- Same SOP-16 footprint family as CH340B/CH340E for drop-in flexibility (vs CH340N (SOP-8))
- Roughly 1/5 the price of FTDI FT232RL at 1k quantities (vs FTDI FT232RL)
Design Notes
Route USB D+ and D- (pins 5 and 6) as a 90-ohm differential pair with matched length, keeping the trace impedance within +/-10% tolerance. Place a common-mode choke or ferrite bead on each line near the USB connector to suppress EMI. The VCC pin (16) requires a 0.1 uF ceramic decoupling capacitor placed within 3 mm of the pin, plus a 4.7 uF bulk capacitor on the USB VBUS rail. Estimated: the SOP-16 footprint allows a 2-layer PCB with proper ground pour under the D+/D- traces.
The V3 pin (pin 4) MUST be tied correctly to match the target MCU's logic level - tying V3 to 5 V with a 3.3 V MCU on TXD will damage the MCU's GPIO. Per the WCH datasheet v3.4 (March 2025 update), V3 must be tied to VCC for 5 V operation, to a 3.3 V regulator for 3.3 V operation, or left floating only in pre-defined configurations. Do not leave V3 floating without consulting the latest datasheet revision, as misuse causes logic-level conflicts and intermittent enumeration failures.
The CH340C draws approximately 7 mA during full-speed USB traffic and 50 uA in suspend per the WCH datasheet. On bus-powered designs this is well within USB 2.0's 100 mA unit-load budget, leaving headroom for downstream circuitry. For self-powered designs, ensure the local 3.3 V or 5 V regulator can source at least 50 mA to handle CH340C plus inrush transients during USB enumeration.
Pins 8 (XI) and 9 (XO) are the external crystal pins and MUST be left unconnected (NC) on the CH340C - the internal oscillator is used. Do not place a crystal footprint on the PCB; doing so wastes board space and can introduce noise coupling into the crystal oscillator circuit. The CH340G and CH340B (crystal mode) require a 12 MHz crystal with 20 pF load capacitors between XI/XO and GND.
Compliance Information
RoHS and REACH compliant per WCH product page. Not AEC-Q100 qualified - CH340C targets consumer/hobbyist markets; for automotive, use a CP2102N-Q1 or FT230XQ-R instead.
