Adafruit
Adafruit ISO1540 Bidirectional I2C Isolator - STEMMA QT / Qwiic
The Adafruit ISO1540 Bidirectional I2C Isolator provides full electrical isolation between two sides of an I2C bus, using the TI ISO1540 chip with 2500 V-RMS...
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The Adafruit ISO1540 Bidirectional I2C Isolator provides full electrical isolation between two sides of an I2C bus, using the TI ISO1540 chip with 2500 V-RMS isolation. It's ideal for separating earth-grounded circuits, reducing noise, or protecting sensitive equipment in power monitoring setups.
Fully bidirectional with support for clock stretching and up to 1 MHz I2C clock rates, each side operates independently at 3V to 5.5V with its own power supply. STEMMA QT / Qwiic connectors on both sides allow solderless wiring, and green LEDs confirm power on each half.
Key Features
- 2500 V-RMS Isolation – Full galvanic isolation between I2C bus sides
- Bidirectional I2C – Transparent data transfer in both directions with clock stretching support
- Up to 1 MHz I2C Clock – Standard, fast, and fast-mode plus compatible
- 3V – 5.5V Per Side – Independent power and logic levels on each side
- ±50 kV/µs Transient Immunity – Protection against high-speed voltage transients
- −40°C to +125°C Operating Range – Industrial temperature rating
- STEMMA QT / Qwiic Connectors – One on each isolated side for solderless wiring
- 10 kΩ Pull-ups – Built-in on both sides, connected to their respective VCC
- Power LEDs – Green LED on each side confirms power is connected
Safety Certifications
- 4242 V-PK isolation per DIN VDE V 0884-11:2017-01
- 2500 V-RMS for 1 minute per UL 1577
- CSA approved per IEC 60950-1 and IEC 62368-1
- HBM ESD protection: 4 kV on all pins, 8 kV on bus pins
Ideal For
- Isolating earth-grounded equipment from microcontroller I2C buses
- Power monitoring systems requiring galvanic isolation
- Noise reduction on I2C buses in electrically noisy environments
- Safety-critical applications requiring certified isolation
Package Contents
- 1× Adafruit ISO1540 Bidirectional I2C Isolator Breakout
- 1× Header Strip
Resources
Jargon buster
Plain-language definitions for the technical terms used above.
- breakout
- A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.
- DIN
- As a pin label, DIN stands for 'data in', the input through which a device receives serial data from a controller, as found on SPI displays, LED drivers and other serial modules. DIN can also refer to the German standards body of that name, as in a round multi-pin DIN connector or DIN-rail mounting.
- ESD protection
- ESD protection helps protect electronics from damage caused by static electricity discharges. It is useful on development boards because cables, sensors and modules are often plugged and unplugged during prototyping.
- I2C
- I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
- LED
- A light-emitting diode (LED) is a small electronic component that emits light when current flows through it in the correct direction. Because it only conducts one way, its polarity matters, and a through-hole LED must be soldered the correct way around to light up.
- microcontroller
- A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.
- Qwiic
- Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.
- RMS
- RMS is a way of describing the effective level of an AC signal, such as an audio output voltage. It helps compare audio output levels more meaningfully than a peak voltage number.
- STEMMA
- A plug-and-cable connection system used on some maker electronics boards to make wiring simpler. If a product uses STEMMA, you need the matching cable or connector type to plug it in without soldering.
- STEMMA QT
- A small plug-in connector system for I2C boards that lets you connect compatible sensors and controllers without soldering. It matters because it can make wiring faster and less error-prone, especially when adding several small modules to a project.
- UPS
- An uninterruptible power supply is a battery-backed power system that keeps a device running when external power is unplugged or fails. For an embedded computer, it helps prevent sudden shutdowns that can corrupt files or interrupt a project.
- VCC
- VCC is the positive power-supply connection on a chip or module. Connecting it to the correct supply voltage is needed for the part to power on and helps avoid damaging the electronics.
Related Tutorials
Free guides on learn.littlebird.com.au