Adafruit LTC4311 I2C Extender / Active Terminator - STEMMA QT / Qwiic

I2C is designed for short-distance communication on a PCB, but extending it over long cables introduces capacitance and resistance that can slow down signals. The Adafruit LTC4311 active terminator solves this by boosting the I2C bus rise times, enabling much faster data rates over long cables without complex hardware changes.

The LTC4311 is easy to use—simply connect it to your I2C bus (usually at the start of the chain). It automatically detects activity on the SCL and SDA lines, providing a strong, slew-limited pull-up current to improve signal integrity. This board supports bus voltages from 1.6V to 5.5V and speeds up to 400 KHz, working effectively even over cables with high capacitance.

Designed in the STEMMA QT form factor, it features connectors compatible with SparkFun Qwiic connectors, allowing solderless chaining with multiple sensors and accessories. Note that QT cables are not included but available separately.

• Improves I2C bus rise times and data integrity
• Wide supply voltage range: 1.6V to 5.5V
• Supports up to 400 KHz clock speed
• Auto detects low power standby mode
• Very low shutdown current <5μA
• Does not load bus when disabled
• ±8kV Human Body Model ESD protection
• STEMMA QT connectors for easy chaining

This board is perfect for projects needing reliable I2C communication over long cables without sacrificing bus speed or signal quality.