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

• Adafruit ISO1540 I2C Isolator Guide