Adafruit LTC4311 I2C Extender / Active Terminator - STEMMA QT / Qwiic
We have ✅ 7 available of the AF-4756 in our Sydney warehouse. An extra 100 units available with a short lead time.
The Adafruit LTC4311 Active Terminator solves a common I2C problem: running long cables. Standard I2C is designed for short PCB-level connections, but cable capacitance and resistance degrade signals over distance. The LTC4311 watches the SDA and SCL lines and actively boosts pull-up current, restoring clean square-wave signals even over multi-metre cables.
Simply plug this board into your I2C bus at the start of the chain — no firmware, software, or configuration needed. In testing, it ran a 400 kHz OLED over 3 metres of phone wire with ease, and even drove a BME680 sensor over 30 metres of Ethernet cable at 100 kHz (~3000 pF round trip).
Key Features
- Active I2C Termination – Boosts pull-up current on SDA and SCL for clean signal edges over long cables
- Wide Voltage Range – Works with any bus voltage from 1.6 V to 5.5 V
- Up to 400 kHz – Supports standard and fast I2C clock speeds
- Cable Capacitance up to 4000 pF – Handles very long cable runs
- Zero Configuration – No firmware, software, or resistor tuning required; just plug in and go
- STEMMA QT / Qwiic – Solderless I2C connectors on both sides for easy daisy-chaining
Ideal For
- Running I2C sensors over long cables (1–30+ metres)
- Fixing unreliable I2C communication on extended buses
- Remote sensor installations connected by phone wire or Ethernet cable
- Any I2C project where cable capacitance is degrading signal quality
Package Contents
- 1× Adafruit LTC4311 I2C Extender / Active Terminator (STEMMA QT)
Resources
The Adafruit LTC4311 I2C Extender / Active Terminator - STEMMA QT / Qwiic appears in the following collections:
