QinHeng USB-to-Serial Converters

About USB-to-Serial Converters

USB-to-serial converter chips for UART, SPI, I2C, and parallel interfaces

As an authorized distributor of QinHeng, BeiLuo provides a comprehensive range of USB-to-Serial Converters products. These products are widely used in industrial control, automotive electronics, consumer electronics, and communication equipment. We offer a complete product line with multiple series to meet various application requirements. All products are genuine and original, backed by professional technical support and comprehensive after-sales service.

Selection Guide: How to Choose the Right USB-to-Serial Converters

Product List

4 products available

Part Number ↕	Interface ↕	Baud Rate ↕	IO Voltage ↕	USB Speed ↕	Handshake ↕	Package ↕	Stock Status	Action
CH340C	USB 2.0 Full Speed to UART	50bps to 2Mbps	5V or 3.3V (selectable)	Full Speed (12Mbps)	RTS, CTS, DTR, DSR, DCD, RI	SOP-16, ESSOP-10, MSOP-10	In Stock	View Details
CH340G	USB 2.0 Full Speed to UART	50bps to 2Mbps	5V or 3.3V (selectable)	Full Speed (12Mbps)	RTS, CTS, DTR, DSR, DCD, RI	SOP-16, DIP-16	In Stock	View Details
CH341A	USB 2.0 Full Speed to UART/SPI/I2C/Parallel	50bps to 2Mbps (UART)	5V or 3.3V (selectable)	Full Speed (12Mbps)	-	SOP-28, SSOP-20	In Stock	View Details
CH347	USB 2.0 Full Speed to SPI/I2C/UART/GPIO	-	3.3V (5V tolerant)	Full Speed (12Mbps)	-	QSOP-28, SSOP-20	In Stock	View Details

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Frequently Asked Questions

What is the maximum baud rate supported by CH340?

CH340 supports baud rates from 50bps to 2Mbps. Common rates like 9600, 115200, 921600 are all supported. The actual maximum depends on the application and USB host capability. At 2Mbps, ensure your UART device can handle the speed and that cable quality is sufficient. The chip uses USB 2.0 Full Speed (12Mbps) interface, providing ample bandwidth for serial communication.

CH340 supports all standard baud rates. For 2Mbps operation, verify your system can handle the speed. Contact our FAE team for high-speed application guidance.

How do I install CH340 drivers on Windows?

Windows 10/11 include built-in CH340 drivers and typically install automatically. For older Windows versions or manual installation: 1) Download drivers from QinHeng website

2) Run installer as administrator

3) Connect CH340 device

4) Windows will detect and install driver

5) Verify in Device Manager under Ports (COM & LPT). If driver doesn't install automatically, manually point to driver folder. WHQL certified drivers ensure compatibility.

Windows 10/11 users typically don't need manual installation. For older Windows or issues, download drivers from our website. Contact our FAE team for driver troubleshooting.

Can CH340 operate at 3.3V IO voltage?

Yes, CH340 supports both 5V and 3.3V IO voltage levels. The VCC pin determines IO voltage - connect to 5V for 5V IO, or 3.3V for 3.3V IO. The USB interface remains at USB standard levels regardless of IO voltage. This flexibility allows direct connection to 3.3V microcontrollers without level shifting. Ensure your PCB design matches the intended IO voltage.

Connect VCC to desired IO voltage (5V or 3.3V). No external level shifter needed for 3.3V systems. Contact our FAE team for mixed-voltage system design.

What is the difference between CH340G and CH340C?

CH340G and CH340C are pin-compatible variants with different clock sources. CH340G requires external 12MHz crystal oscillator. CH340C has built-in clock oscillator, eliminating external crystal and reducing BOM cost. CH340C is recommended for new designs due to simpler design and lower cost. Both offer identical USB and UART functionality. CH340E is a smaller package variant with fewer handshake signals.

Use CH340C for new designs (No crystal is needed). Use CH340G if you need external clock source. Contact our FAE team for variant selection.

How do I use CH341 in SPI or I2C mode?

CH341 operates in different modes selected by configuration pins or EEPROM. For SPI mode: configure MODE0/MODE1 pins for SPI, connect to SPI device using SCK, MOSI, MISO pins. For I2C mode: configure for I2C, use SDA and SCL pins. The CH341 DLL/API provides functions for SPI/I2C transactions. Windows drivers include DLL interface. Linux uses i2c-dev or spidev interface. Application examples are provided in QinHeng SDK.

Configure CH341 mode pins for desired interface. Use provided DLL/API for communication. Contact our FAE team for SPI/I2C application examples.