CH341A PDF – EEPROM Flash BIOS USB Programmer

This post explains for the USB-Interface-Chip.

The Part Number is CH341A.

The function of this semiconductor is USB bus convert chip for EEPROM Flash BIOS USB Programmer.

The Package is DIP, SSOP 28 Pin

Manufacturer: Nanjing Qinheng Microelectronics ( )

See the preview image and the CH341A datasheet PDF file for more information.


CH341A datasheet

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CH341A image


The CH341A is a USB bus convert chip, providing UART, printer port, parallel and synchronous serial with 2-wire or 4-wire through USB bus. In UART mode, CH341 provides alternant rate control signals such as serial transfer enable, serial receive in ready etc.

It also supplies common MODEM communication signal in order to expand UART for computer or upgrade common synchronous interface device to USB bus directly. In printer port mode, CH341 supplies standard USB printer port which compounds USB relevant protocol and Windows operate system used to upgrade ordinary parallel printer to USB bus directly. In parallel mode, CH341 gives out 8-bit parallel in EPP or MEM mode. It can be used to input/output data directly without MCU/DSP. Besides, CH341A also supports some common synchronous serial such as 2-wire (SCL, SDA) and 4-wire (CS, SCK/CLK, MISO/SDI/DI […]

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Reference Site: CH341A Programmer : 8 Steps – Instructables


1. Full speed USB device interface, conforms to USB Specification Version 2.0, only needs crystal and
capacitance external.

2. Optional: define Vender ID, production ID and list number through external low-cost serial EEPROM.

3. Supports 5V and 3.3V power source.

4. Low-cost, directly convert serial peripheral equipment, parallel printer and parallel peripheral

CH341A Datasheet