Custom ISO1540 bidirectional I2C isolator - STEMMA QT/For Qwiic

Note: This product is purple plate

describe

Sometimes you'll find an I2C bus controller on one side and an I2C bus device on the other, and you have to separate them. Maybe because one of them is grounded, maybe because you have some snazzy power monitors, maybe you want to reduce the noise.

Whatever it is, you can add complete electrical isolation between the two ends of the I2C bus using the ISO1540 bidirectional I2C isolator. The chip we use, the TI ISO1540, is fully bidirectional, supports clock rates up to 1 MHz, supports clock stretching, works on 3 to 5V DC power or logic (separate sides of course), and has 2500 V-RMS isolation

It's easy to use - you get power/ground/clock/data disconnect pads for each side as well as a matching STEMMA QT connector. Unlike our other QT boards, the sides are obviously electrically isolated, which means each half must be powered! Check that the green LED is on. Now send the data via I2C and you're ready to go. We have 10K pull-outs on each side from the I2C pin to the corresponding VCC.

To make you go faster, we've rotated a custom PCB in the form factor of STEMMA QT to make it easy to interface. STEMMA QT connectors on both sides are compatible with SparkFun I2C connectors. This allows you to make solderless connections between the development board and ISO1540, or connect it to a wide range of other sensors and accessories using compatible cables. QT cables are not included, but we have a variety of cables in the store.

ISO1540 features

Isolated bidirectional, I2C compatible, communication

Supports operations up to 1-MHz

3-V to 5.5v power supply range

The open drain output has 3.5 mA side 1 and 35 MA side 2 sink current capabilities

Operating temperature from -40°C to +125°C

±50kv /μs transient immunity (typical)

HBM ESD protection on all pins is 4kv; The bus pin has a voltage of 8kv