USB to UART Bridge Controller CH340


CH340 is a USB converter chip, which converts USB to serial UART interface or to printer interface. In UART mode, CH340 provides common MODEM interface signals, to expand UART interface of computer or upgrade common serial communication devices to USB directly. For more information about converting USB to printer interface, please refer to the datasheet CH340DS2.


  • Full speed USB device interface, USB 2.0 compatible.
  • Emulate standard UART interface, used to upgrade the original serial devices or expand additional UART via USB.
  • Original UART applications are totally compatible without any modification.
  • Hardware full duplex serial UART interface, integrated transmit-receive buffer, supports communication baudrates varies from 50bps to 2Mbps.
  • Supports common MODEM interface signals RTS, DTR, DCD, RI, DSR and CTS.
  • Provides further RS232, RS485, RS422 interface, etc. through external voltage conversion chip.
  • CH340R supports IrDA specification SIR infrared communication, supports baudrates varies from 2400bps to 115200bps.
  • Software compatible with CH341, customers can use driver of CH341 directly.
  • Supports 5V and 3.3V power supply even supports as low as 3V.
  • CH340C/N/K/E and CH340B integrate 12MHz clock, no external crystal required, CH340B also integrates EEPROM used to configure the serial number, etc.
  • RoHS compliant SOP-16, SOP-8, SSOP-20 and ESSOP-10, MSOP-10 lead-free package.


Model differences: CH340C, CH340N, CH340K, CH340E and CH340B integrate 12MHz clock, no external crystal required. CH340B integrates EEPROM used to configure the serial number, etc. Some functions can be customized. The CH340K has three diodes built in to reduce current flow backwards between the I/O pins of the MCU. The backplane of the CH340K is 0# pin GND, which is an optional connection; the 3# pin GND is the necessary connection. CH340R provides reverse polarity TXD and MODEM interface signals. (Discontinued).

Development Information Datasheet: CH340DS1.PDF Drivers: 1.CH341SER.EXE(Windows driver, supports WIN10/WIN8/WIN7/XP etc.) 2.CH341SER_ANDROID.ZIP(Android application) 3.CH341SER_LINUX.ZIP(Linux driver) 4.CH341SER_MAC.ZIP(MAC OS driver) Schematic/PCB: CH340PCB.ZIP

relation files

file name file content
CH341SER.EXE CH340/CH341 USB to serial port Windows driver, supports 32/64-bit Windows 10/8.1/8/7/VISTA/XP, Server 2016/2012/2008/2003, 2000/ME/98,Microsoft WHQL Certified, supports USB to 3 and 9 wire serial ports. Used to distribute to the end user with the product.
CH341DS1.PDF CH341 datasheet, USB bus converter chip with multiple communication interfaces, such as USB to serial port/parallel port/printer port/I2C interface etc. Drivers support for Windows/Linux/Android/Mac, etc. The datasheet is the description of USB to serial port and printer port.
CH438DS1.PDF CH438 datasheet. CH438 is an 8-UART extension chip. Each UART receive/transmit has independent 128-byte FIFO. The maximum baud rate is 4Mbps. It supports hardware flow control, compatible with 16C550/16C750. It provides 8-bit parallel interface, used for MCU 8-UART extension.
CH341SER_ANDROID.ZIP CH340/CH341 USB to serial port Android free drive application library, for Android OS 3.1 and above version which supports USB Host mode already, no need to load Android kernel driver, no root privileges. Contains apk, lib library file (Java Driver), App Demo Example (USB to UART Demo SDK).
CH9340DS.PDF CH9340 datasheet, USB CDC to single serial port, built-in crystal oscillator, supports built-in CDC driver in operating system.