Isolated FT230X

Small board to isolate your FTDI interface

A board based upon the Sparkfun FTDI board but improved with an Digital Signal Isolator!

The main goals are to reduce noise inserted into your project by cheap laptops, and prevent any unnecesary ground loops. While still maintaining mains voltage isolation purposes for those times your target is not earth referenced but your pc is. This project keeps it simple, which might not be the cheapest. 

This little board is about 45 mm by 15 mm, it is equipped with an FT230XQ USB to Serial bridge and an ADUM1402  to provide full circuit isolation between your device under test and your PC.

The SMD female connector on the bottom side is pincompatible with a standard FTDI TTL cable. This results in a fully featured isolated UART interface with your device.

The USB connector is a USB Type B (5-pin), the most commonly used one. I didn't fit it with Micro USB since that connector is horrible if you look at orientation and sturdyness.


These specifications are based on the ADuM1402ARW

  • FTDI FT230X chip
  • 500 Vac (peak) or 1000 VDC isolation. Which should be more than enough for anything you build at home.
  • 1 Mbps datarate, more than enough for the most common 9600 8N1 serial port.
  • Approximately 1 mA of current required for the isolated side on 256000 baud.
  • 3 to 5 Volt operation, limited by the operation voltage of the ADuM isolator. Does not include power supply for target side.
  • RX and TX LED


  • Board, 1$
  • ADuM1402ARW, 5$ (pin compatible with Silabs Si8642 family of digital isolators)
  • FT230XQ, 5$
  • Some ceramic capacitors, some resistors and a ferrite bead 2$
  • And some connectors, 5$
  • Total price approximately 20$ (parts only)


Download the eagle project or the gerber files.