Qinheng third generation USB to dual serial port chip CH342

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Qinheng third generation USB to dual serial port chip CH342 [Copy link]

This post was last edited by qwqwqw2088 on 2021-6-9 08:20

The USB to serial port chip CH342 is used to expand 2 high-speed asynchronous serial ports for the USB host, supporting a serial port baud rate of up to 3Mbps. It is the third generation of USB to serial port products launched by Qinheng. CH342 is a CDC serial port chip that can be plug-and-play on most operating systems without the need to install additional drivers. At the same time, it provides manufacturer drivers to support more functions and higher communication rates;

Each serial port has a built-in transceiver buffer and works independently without affecting each other. It is highly integrated internally, streamlined peripherals, provides VIO power pins, and the serial port I/O supports independent power supply.

Features
Overview
1. Full-speed USB device interface, compatible with USB V2.0.

2. Built-in USB controller and transceiver.

3. Built-in clock for USB and serial port operation.

4. Built-in USB signal line requires series matching resistors and pull-up resistors.

5. Built-in firmware, built-in power-on reset.

6. The USB port supports 5V power supply voltage and 3.3V power supply voltage.

7. Provide lead-free packages such as QFN/ESSOP, compatible with RoHS.

Asynchronous serial port
1. Hardware full-duplex serial port, built-in independent serial port send and receive buffer.

2. The serial port I/O is independently powered and supports 5V/3.3V/2.5V/1.8V power supply voltage.

3. The serial port supports 5/6/7/8 data bits, 1/1.5/2 stop bits, and supports odd/even/mark/blank/no parity.

4. Support common MODEM communication signals RTS, DTR, DCD, RI, DSR, CTS.

5. Support CTS and RTS hardware automatic flow control.

6. Support half-duplex, provide TNOW signal of sending status and support RS485 switching.

7. Support RS232/RS422/RS485 and other interfaces through external level conversion chip.

Driver mode
1. Supports installation-free operating system built-in CDC class drivers or multi-function high-speed VCP manufacturer drivers.

2. Emulate standard serial port, the host side recognizes it as a virtual serial port, and the serial port application is fully compatible without modification.

Function
Power Description
The CH342 chip has 3 power terminals and a built-in 3.3V power regulator.

1. VDD5 is the input of the internal power regulator.

2. V3 is the output of the power regulator and the input of the USB transceiver and core power supply.

3. VIO is the I/O pin power supply.

The chip supports 5V or 3.3V power supply voltage, and the V3 pin is always connected to a 0.1uF decoupling capacitor. When the 3.3V power supply voltage is working, V3 also needs to be connected to the VDD5 pin and input an external 3.3V power supply at the same time.

The VIO pin of the chip is used to provide I/O power for the serial port I/O and other pins, supporting a power supply voltage of 1.8V~5V. VIO should use the same power supply as the MCU and other peripherals. This can effectively prevent current backflow between serial port devices through the IO pins.

Serial port description
The asynchronous serial port of the chip transfer defaults to TTL level. When the serial port input/output is idle, RXD/TXD should be high level, and the level value should be consistent with the VIO power supply.

The allowable baud rate error of the chip serial port receiving signal is no more than 2%, and the baud rate error of the serial port sending signal is less than 1.5%.

In applications with high communication baud rates, it is recommended to enable hardware automatic flow control.

The serial port MODEM signal can be controlled and defined by the serial port application. Usually: RTS and DTR signals can be used as general output signals, which are common in MCU download scenarios.

Typical application circuit

CH342 Technical Manual

CH342DS1.PDF (198.09 KB, downloads: 12)

Schematic Reference Design

CH342EVT原理图参考设计.ZIP (341.84 KB, downloads: 9)

Windows Driver

CH342/CH343/CH9102 USB to high-speed serial port WINDOWS manufacturer driver, supports 32-bit and 64-bit windows 2000/XP/Vista/7/8/8.1/10/SERVER 2003/2008/2012/2016/2019, supports USB to 3-wire and 9-wire serial ports, supports the highest baud rate, for distribution to end users with the product.

CH343SERWindows驱动1.ZIP (157.98 KB, downloads: 10)

CH342/CH343/CH9102 USB to CDC serial port WINDOWS driver installation package, supports 32-bit and 64-bit Windows 2000/XP/Vista/7/8/8.1/10/SERVER 2003/2008/2012/2016/2019, supports USB to 3-wire and 9-wire serial ports, etc., for distribution to end users with the product.

CH343CDCWindows驱动2.ZIP (70.62 KB, downloads: 6)