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