Per-Simon Saal Releases the "Smallest I2C Isolator with Power" for Qwiic/STEMMA QT Projects

Delivering up to 1W of power and a choice of 3.3V or 5V isolated I2C signals, this tiny board is a drop-in fix for a range of issues.

Gareth Halfacree
2 months agoHW101

Electrical engineer Per-Simon Saal has designed what he claims is the "smallest I2C isolator with power," designed to drop into any Qwiic/STEMMA QT circuit where noise is preventing a clean signal or where electrical isolation is desired.

"This is likely the smallest PCB that combines I2C and power isolation in a compact design," Saal explains of his creation. "It delivers 1W of isolated output power, all within an extremely small form factor. It connects seamlessly to your microcontroller project using a STEMMA QT (JST SH 4-pin) cable, ideal for isolating your sensor board."

Inspired, Saal says, by recent advancements in miniaturizing DC-DC converters, the tiny board is powered by a Texas Instruments ISO1641 I2C isolator and a Monolithic Power Systems MIE1W0505BGLVH DC-DC power converter. With a 3.3V input, it outputs a clean and electrically-isolated 3.3V I2C signal; with a 5V input, it can output the user's choice of 3.3V or 5V output chosen via a solder bridge on the underside of the board.

Designed for a minimal footprint, Saal says the board can be used for any project where electrical isolation is required — or used to boost the signal integrity over long wiring runs, in environments where electrical noise is interfering with the I2C signal, or to prevent ground loop issues.

Saal has uploaded a KiCad project for the isolator board to GitHub under the permissive MIT license, and is selling assembled units on Tindie for $18 — plus a dollar if you'd like a length of heatshrink tubing to apply to the board.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
Latest articles
Sponsored articles
Related articles
Latest articles
Read more
Related articles