Overview of CH340 USB Converter Chip

CH340 Pinout

CH340 is a USB bus convert chip that can convert USB to serial, USB to IrDA infrared, or USB to printer interface.

In serial interface mode, the CH340 provides a common MODEM liaison signal, which can be used to expand a computer's asynchronous serial interface or immediately upgrade a common serial device to the USB bus. Please refer to the second manual CH340DS2 for more information on the USB convert to printer interface.

In infrared mode, a USB infrared adapter can be created by adding an infrared transceiver to the CH340, allowing for SIR infrared communication.

• Full speed USB 2.0

• Emulates standard serial interface, can be used to upgrade older equipment to USB

• Baud rate from 50bps to 2Mbps

• 5V and 3.3V power

• SSOP-20 package

• CH340 Applications

• USB to UART conversion

• Upgrading old devices to USB

• Programming microcontrollers

• USB to UART conversion

• Upgrading old devices to USB

• Programming microcontrollers

FT232, CH340G

The CH340 is a simple USB to serial IC that converts USB signals to UART, which is used to interface with older appliances and microcontrollers.

Because the ATMega329P utilized in these boards does not have built-in USB functionality, it communicates with a computer via a UART interface, which is translated to USB using the CH340.

CH340 Circuit

The data connections on the UART side are provided by connecting the TX and RX serial pins to pins PD0 and PD1 of the microcontroller, respectively. Another noteworthy feature is that the DTR pin is connected to the reset pin via a capacitor, which resets the microcontroller whenever a serial connection or USB connector is plugged in. On the USB side, the D+ and D- pins are linked to the USB connector's respective pins. A USB clock is also provided by a 12MHz crystal (together with its load capacitors). The CH340 can be used as a simple USB to serial interface with this simple circuit setup.

The biggest difference is the USB interface. The real one uses a CP2102 USB to UART Bridge. The copy uses a CH340G chip. The CH340G is notoriously unstable and liable to die at a moment’s notice.

CH340 Dimension

Nanjing Qinheng Microelectronics Co., Ltd., formed in 2004, is a business that specializes in RF and high-speed digital-analog mixed Integrated Circuit design, as well as MCU core research. Ethernet, Bluetooth wireless network, USB, and PCI interface chips, as well as MCU + microcontroller integrated with the above interfaces, are all available from us. ADC/PGA and other analog detection, MCU smart control and driving algorithm, HID human-computer interaction, Ethernet/Bluetooth-LE and other network communications, UART/USB/USB PD/PCIE/CAN/SerDes and other interface communications, data security, IoT protocol, and cloud service are all part of our technology.