The PL2303 USB UART Board (mini) is an accessory board that features a USB-to-UART serial convert PL2303, USB mini-AB connector, and 3 LEDs: TXD LED, RXD LED, POWER LED.

There is also a jumper used for selecting VCC output level provided on the board:

• Short the jumper to select output voltage level as 5V or 3.3V. In this case, the accessory board is powered from USB connection and provides power to the target application board
• If the jumper is open, the accessory board should be powered from the target application board (3.3V-5V)