USB to TTL UART Isolated for Arduino pro mini


21 in stock

Range Discount
10 - 24 5%
25 + 10%


This project has been successfully founded on KickStarter!

What is it?

It’s a USB to UART converter with a digital isolator at the UART side. It has a micro USB for connecting to the PC and a 6 pin header with the same pin-out of the Arduino Pro mini board.


I was using a cheap USB serial converter, but sometimes they didn’t work correctly and I was losing time. The chip FT231X is used as interface between the USB and the UART protocol, while the Si8642 is used for isolate the board from the PC. This converter is very useful if you are working on some projects and worrying about short circuit with the main power supply. Because the isolator isolates the two sides therefore there is no electrically connection.


  • You don’t burn your PC in case of some accidents between your project and the main power supply. Check our test!
  • The noise from your PC doesn’t enter in your project.
  • Your project and the PC have isolated ground.
  • Voltage levels of the UART are the same of the power supply of your project.
  • Your project is not powered from the USB of the PC, so you don’t have power issue when you power off your project.

Technical data

  • Original FTDI FT231X: Compatible with almost all the operating systems and capable of variety baud rates of 300 baud to 3 Mbaud
  • Original Si8642BB-B-IS1: Low-Power Quad-Channel Digital Isolators with isolation rating up to 2.5kV
  • Size of 40 x 17mm.
  • 4.1mm isolation between the two sides guarantee an electrical isolation up to 1kV
  • Working between 2.5V to 5V.
  • TX and RX LEDs indicators.
  • Micro USB connector.
  • Standard 2.54mm 6 pins female header.
  • Protected by a transparent heat shrink sleeve.


Name Description Direction Voltage level
Ground Input 0V
CTS Clear To Send input same of +
+ Positive power supply Input 2.5V – 5V
TX UART TX output same of +
RX UART RX input same of +
DTR Data Terminal Ready output same of +