CH340G - USB to UART Bridge IC, SOP-16, 2 Mbps | WCH
MPN: CH340G ✓ AktifCH340G Genel Bakış
A USB-to-UART bridge (also called a USB-serial converter) is an interface controller that translates USB packets into asynchronous UART frames and vice versa, allowing microcontrollers that lack native USB (such as the ATmega328P, ESP8266, or older PIC parts) to communicate with a host PC through a standard COM port. USB-UART bridges sit one layer below the USB protocol stack and above the bare UART peripheral, transforming what would otherwise require a complex HID/CDC firmware stack into a transparent virtual COM port. CH340 fits into the broader taxonomy of interface ICs -> bus converters -> USB bridges.
Key features of the CH340G include full USB 2.0 full-speed device compatibility, hardware flow control on CTS/RTS, automatic transmitter/receiver buffer management, modem signals (RI, DCD, DTR, DSR), and 5V-tolerant IO when VCC is 5V. The device enumerates as a CDC-class device on Windows/macOS (driver required on Windows) and as a CDC-ACM device on Linux/Android without additional drivers. The SOP-16 footprint is the most widely used package for hobbyist Arduino Nano and NodeMCU/ESP-12E boards.
The CH340G uses an external 12 MHz fundamental-mode crystal feeding an internal PLL to derive the 48 MHz USB clock and the configurable UART baud-rate generator. Internal UART FIFOs buffer transmit and receive traffic, and the chip supports common baud rates from 50 bps up to 2 Mbps as well as non-standard rates generated through a divisor setting. The R232 assistant pin enables RS-232 polarity translation in software, eliminating the need for an external MAX232 in many point-to-point designs.
Typical applications include Arduino Nano and Arduino Nano-compatible clones, ESP8266/ESP-12E serial programmer boards (NodeMCU, Wemos D1), industrial USB-to-RS232 adapters, USB-to-RS485 converter dongles, and as a low-cost debug serial bridge on custom MCU boards. It is also used in label printers, GPS receivers, and barcode scanners that need USB connectivity for legacy UART peripherals.
When designing with the CH340G, ensure the 12 MHz crystal is placed within 5 mm of the XTI and XTO pins with a guard ground to avoid radiated emissions that can fail USB compliance. Decouple VCC with a 100 nF ceramic cap adjacent to pin 16 and a 4.7 uF bulk cap on the 3.3 V rail. The V3 pin should be left floating when using a 5 V supply or tied to a 3.3 V LDO when using a 3.3 V supply.
This page synthesizes distributor pricing from LCSC, drop-in pin-compatible alternatives from the CH340 family, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatifler için CH340G — aynı paket, pin-başına uyumlu. PCB yeniden montajı gerektiren farklı paket bileşenleri dışlanmıştır.
Bu Serideki Variantlar
Yedek parça uyumlu olan aynı serideki modeller CH340G (aynı form faktörü ve ayağa oturma) — farklı olan Operating Temperature, Manufacturer, Package, Product Type, Driver Support.
CH340C
✅ YerleştirmeFiyat için iletişime geçin
Veri Şablonunu Görüntüle →CH340B
✅ Yerleştirme📋 Katalogda Olmayan Referans Alternatifi
CH340T
✅ Yerleştirme ⚠️ Onaylanmamış Özellikler📋 Katalogda Olmayan Referans Alternatifi
CH340N
✅ Yerleştirme ⚠️ Onaylanmamış ÖzelliklerFiyat için iletişime geçin
Veri Şablonunu Görüntüle →CH340G Özellikler
| Product Type | USB to UART Bridge Controller |
| Manufacturer | WCH (Nanjing Qinheng Microelectronics) |
| USB Specification | USB 2.0 Full-Speed (12 Mbps) |
| Supply Voltage (VCC) | 3.3 V to 5 V |
| IO Logic Level | 3.3 V or 5 V (matches VCC) |
| Operating Baud Rate | 50 bps to 2 Mbps |
| UART Signals | TXD, RXD, CTS, RTS, DTR, DSR, DCD, RI |
| Clock Source | External 12 MHz crystal required |
| İşletim Sıcaklığı | -40 C to +85 C |
| Storage Temperature | -40 C to +125 C |
| Maximum VCC | 6.5 V (absolute max) |
| IO Pin Voltage Range | -0.5 V to VCC + 0.5 V |
| Paket | SOP-16 (SOIC-16, 150 mil) |
| Montaj Türü | Surface Mount |
| RS-232 Assistant Mode | Yes (R232 pin enables internal inverter) |
| RoHS Durumu | Compliant |
CH340G Pin Yapısı
| Pin 1 | XTI — Crystal oscillator input (12 MHz) |
| Pin 2 | XTO — Crystal oscillator output (12 MHz) |
| Pin 3 | UD+ — USB D+ data line |
| Pin 4 | UD- — USB D- data line |
| Pin 5 | GND — Ground reference |
| Pin 6 | VCC — Power supply input (3.3 V to 5 V) |
| Pin 7 | R232 — RS-232 assistant enable (drive high to invert RXD polarity) |
| Pin 8 | TXD — UART transmit output |
| Pin 9 | RXD — UART receive input (or R232-inverted RX when R232 high) |
| Pin 10 | V3 — Internal 3.3 V LDO output (decouple with 4.7 uF); tie to VCC for 5 V or float for 3.3 V use |
| Pin 11 | CTS — Clear-to-send handshake input |
| Pin 12 | RTS — Request-to-send handshake output |
| Pin 13 | DSR — Data set ready modem input |
| Pin 14 | DTR — Data terminal ready modem output (commonly used for auto-reset) |
| Pin 15 | DCD — Data carrier detect modem input |
| Pin 16 | RI — Ring indicator modem input |
Tipik Uygulamalar
CH340G için uygundur 7 uygulamas: Arduino Nano V3 Clone, ESP8266 / NodeMCU USB Programming, USB to RS-232 Converter Dongle, Industrial USB to RS-485 Bridge, USB Barcode Scanner / Label Printer Interface, ESP-12E USB Programming Cable Replacement, Custom MCU Development Board Debug Port.
Arduino Nano V3 Clone
The WCH CH340G serves as the USB-to-UART bridge on virtually every Arduino Nano V3 clone, replacing the more expensive FT232RL to drive the ATmega328P's UART0 (pins D0/D1). Why the CH340G fits: with 5 V VCC, the UART pins deliver 5 V CMOS levels directly to the ATmega328P without a level shifter, and the 2 Mbps maximum baud rate covers the 115200 bps upload rate used by Arduino IDE. How it is used: the CH340G's TXD pin drives the ATmega328P RX, while CTS/RTS handshaking is wired to the auto-reset circuit for bootloader trigger; DTR drives the reset MOSFET through a 100 nF cap. Performance consideration: total BOM cost drops by roughly $1.50 compared to an FT232RL design at 1k volume, but Windows users must install the WCH CH340 driver once.
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ESP8266 / NodeMCU USB Programming
The WCH CH340G is the standard USB-UART bridge on NodeMCU v2/v3 ESP-12E development boards, providing the serial link used to flash and debug the ESP8266 over its UART0 (GPIO1/GPIO3). Why the CH340G fits: at 3.3 V operation it produces 3.3 V CMOS levels that match the ESP8266's strict 3.3 V IO requirement, avoiding the regulator overhead needed by 5 V-only bridges. How it is used: TXD and RXD cross to the ESP8266 UART, with RTS driving GPIO0 low for flash-mode entry and DTR via a MOSFET-reset circuit providing the auto-reset needed for esptool.py uploads. Performance consideration: the external 12 MHz crystal holds timing to within the 100 ppm USB spec, so flash-mode handshakes succeed reliably even on long USB cables in the lab; replaceable pin-for-pin with CH340C if you redesign to remove the crystal.
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USB to RS-232 Converter Dongle
The WCH CH340G's R232 assistant pin enables single-chip USB-to-RS-232 conversion without an external MAX232 in many designs, cutting BOM cost and board space. Why the CH340G fits: tying R232 (pin 7) high inverts the RXD path so signals leaving TXD and arriving on RXD meet EIA-232 polarity, and the 5 V VCC level directly drives the charge-pump-free DB9 output through a few mA of current per pin. How it is used: TXD, RTS, DTR, DSR, DCD, and RI are level-shifted with discrete NPN/PNP transistors or a Sipex SP3232EEY to deliver true EIA-232 +/-5 V swing; the external 12 MHz crystal on the SOP-16 keeps timing stable for 115200 bps industrial traffic. Performance consideration: for full EIA-232 compliance above 3 m output drive, pair the CH340G with a level shifter; the WCH datasheet marks the R232 path as an 'assistant' function, suitable for most debug and configuration scenarios.
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Industrial USB to RS-485 Bridge
The WCH CH340G provides the USB-to-UART half of a USB-to-RS-485 converter, paired with a half-duplex RS-485 transceiver such as the MAX3485 or SP485E for industrial fieldbus and Modbus RTU applications. Why the CH340G fits: the SOP-16 footprint and 5 V IO enable a compact dongle reference design, and 2 Mbps UART throughput exceeds the 115200 bps needs of Modbus RTU and most Modbus TCP gateways by a wide margin. How it is used: the CH340G's TXD drives the SP485E driver input, RXD returns through the receiver output, and a GPIO toggles DE/RE for direction control; the external 12 MHz crystal keeps the baud-rate generator within Modbus timing tolerances of 2%. Performance consideration: industrial designers should add 600 W surge protection on the DB9 lines and a 100 nF decoupling cap adjacent to the CH340G VCC pin to survive 15 kV ESD strikes; the -40 C to +85 C operating range supports cabinet-mounted applications.
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USB Barcode Scanner / Label Printer Interface
The WCH CH340G is widely used inside low-cost USB barcode scanners and label printers to convert the device's internal UART (often from an ARM Cortex-M0 MCU such as the STM32F072 or GD32F130) into a virtual COM port for POS software. Why the CH340G fits: the SOP-16 footprint fits inside the scanner housing, and the 50 bps to 2 Mbps range covers legacy serial barcode protocols as well as modern high-speed label rendering streams; the integrated full USB 2.0 full-speed device core avoids external PHY components. How it is used: the MCU's USART1 connects to the CH340G's UART pins, and Windows POS software opens the virtual COM at 9600 to 921600 bps; the WCH CH340 driver installs as a CDC class device. Performance consideration: compared to CDC firmware implemented on the host MCU, using the CH340G offloads the entire USB protocol stack and frees roughly 16 KB of flash and 2 KB of RAM on the embedded MCU.
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ESP-12E USB Programming Cable Replacement
The WCH CH340G is embedded directly into ESP-12E and ESP-12F module carrier boards (Wemos D1 mini, NodeMCU, generic USB-ESP adapters) so that no external FTDI cable is needed. Why the CH340G fits: at the module's 3.3 V supply, the SOP-16 footprint sits on the breakout board alongside voltage regulators and reset circuits; the external crystal holds timing even when the ESP8266 is in deep-sleep and refraining from clocking the bus. How it is used: TXD/RXD cross to the ESP-12E's primary UART, with the CH340G's RTS pin driving GPIO0 low via a 10 kohm pulldown for bootloader entry; during normal operation, TXD/RXD pass transparent 115200 bps text. Performance consideration: each USB-to-ESP module saves roughly $15 in FTDI cable cost per workstation, while the WCH CH340 driver installs on every Windows box once and then transparently enumerates subsequent units.
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Custom MCU Development Board Debug Port
The WCH CH340G is the lowest-cost USB-to-UART option for hobbyist and small-batch custom MCU development boards, typically added as a debug/programming header to STM32 Blue Pill clones, RP2040 boards, and Arduino-compatible variants. Why the CH340G fits: at $0.34 per unit, it undercuts the FT232RL by a factor of ten, allowing manufacturers to put a USB-C connector on every custom board without inflating the BOM; the SOP-16 footprint is small enough to fit next to a 4-pin SWD header. How it is used: USART1/2 on the host MCU routes to TXD/RXD, with DTR through a MOSFET resetting the MCU for auto-flash via STM32CubeProgrammer or pyOCD; the external 12 MHz crystal is omitted in favor of CH340C if the SOP-16 footprint allows the no-crystal pinout. Performance consideration: developers accept the Windows driver install step in exchange for the $1.40 BOM savings per unit; the 2 Mbps UART ceiling covers all Cortex-M0/M4 debug print streams without bottleneck.
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Önerilen Ürünler Özeti
Mühendislik referans verileri: CH340G — karşılaştırma, tasarım rehberi ve uyumluluk bilgileri.
Seçim Kılavuzu
Alternatiflerle Karşılaştırma
| Parametre | Bu Ürün | CH340C | CH340B | CH340T | CH340N |
|---|---|---|---|---|---|
| Brand | WCH (Nanjing Qinheng) | WCH | WCH | WCH | WCH |
| Package | SOP-16 | SOP-16 - same | SOP-16 - same | SOP-16 - same | SOP-8 - different |
| Clock Source | External 12 MHz crystal | Internal oscillator (no crystal) | Internal oscillator (no crystal) | External 12 MHz crystal | Internal oscillator (no crystal) |
| Operating Voltage | 3.3 V to 5 V | 3.3 V to 5 V | 3.3 V to 5 V | 3.3 V to 5 V | 3.3 V to 5 V |
| Max Baud Rate | 2 Mbps | 2 Mbps | 2 Mbps | 2 Mbps | 2 Mbps |
| USB Specification | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed |
| RS-232 Assistant | Yes (R232 pin) | Yes (R232 pin) | Yes (R232 pin) | Yes (R232 pin) | Yes (R232 pin) |
| Unit Price (1k qty) | ~$0.31 | ~$0.32 | ~$0.36 | ~$0.38 | ~$0.30 |
Ana Farklılayıcılar
- External crystal retains pin-compatible upgrade path to internal-oscillator CH340C/CH340B (karşılaştırma:CH340C)
- Lowest unit cost USB-to-UART bridge with SOP-16 footprint (karşılaştırma:CH340B)
- Higher pin count than CH340N preserves full modem-signal breakout (karşılaştırma:CH340N)
Tasarım Notları
Place the 12 MHz fundamental-mode crystal within 5 mm of the XTI/XTO pins (pins 1 and 2) with a guarded ground pour. Length-match the XTI and XTO traces to within 1 mm to avoid duty-cycle asymmetry that fails USB compliance. Add 20 pF load caps from each crystal pin to GND as specified in the CH340G datasheet.
Decouple VCC (pin 6) with a 100 nF X7R ceramic placed within 2 mm of the pin and a 4.7 uF bulk cap on the same rail. The internal 3.3 V regulator output at pin 10 (V3) must be decoupled with 4.7 uF; tie V3 to VCC when running at 5 V, or leave it floating (drawing from internal LDO) when running at 3.3 V. Estimated: at 50 mA load, the internal LDO drops ~200 mV at 5 V input.
Windows 7/8/10/11 requires the WCH CH340 driver (ch341ser.exe) to enumerate the virtual COM port. macOS and Linux/Android include CDC-ACM drivers natively so no install is needed. Counterfeit CH340 chips from unverified sources are common on AliExpress; legitimate WCH parts have a date/lot code on the top marking and may exhibit reduced USB signal integrity if counterfeit.
Uyumluluk Bilgisi
RoHS compliant per WCH product literature; not AEC-Q100 qualified - not recommended for automotive under-hood use; lead-free SOP-16 package per LCSC listing.
