Adafruit LTC4311 I2C Extender / Active Terminator (STEMMA QT / Qwiic)

The Adafruit LTC4311 Active I2C Terminator is the perfect solution for extending I2C communication over long cables or noisy environments without sacrificing performance. I2C is typically used for short distances, but when you attempt to use it over long cables (greater than a meter), you often run into issues with capacitance and resistance slowing down the communication, making it difficult to maintain higher clock speeds (100KHz or more). Rather than drastically reducing the clock speed to compensate, the LTC4311 can help you keep your data rates high and stable.

Key Features:

• Boosts I2C Performance: This active terminator compensates for the resistance and capacitance that build up over long cables, allowing you to use I2C at high speeds (up to 400 KHz) even with long cables (up to 4000pF round-trip capacitance).
• Easy Setup: Simply connect the SCL (clock), SDA (data), power, and ground pins to your I2C bus. No special firmware, software, or complex configuration needed. The device automatically activates when it detects the I2C lines being pulled up.
• Voltage Compatibility: It works with bus voltages ranging from 1.6V to 5.5V, making it suitable for a variety of devices and systems.
• Tested Performance: With the LTC4311, we successfully ran a 400 KHz OLED display over 3 meters of phone wire, and even ran a BME680 sensor over 100 feet of Ethernet cable with a 100KHz signal, showing data on an OLED display.

Additional Benefits:

• STEMMA QT Form Factor: To make things easier, the terminator comes in a STEMMA QT form factor, which is compatible with the SparkFun Qwiic I2C connectors. This allows for quick, solderless connections to your development board and makes it simple to chain other I2C sensors and accessories.
• No Extra Components Required: There's no need for additional resistors or adjustments to your I2C setup. Just plug it in, and the rise times of your signal will be smoothed out, turning noisy, uneven waveforms into clean square waves.

The LTC4311 Active I2C Terminator is ideal for projects where you need reliable I2C communication over long distances, whether for sensors, displays, or other devices. It’s a simple plug-and-play solution for improving I2C performance without the hassle.

Technical Details:

LTC4311 Features & Specifications

• Improves I2C Bus Rise Time Transition
• Ensures Data Integrity with Multiple Devices on the I2C Bus.
• Wide Supply Voltage Range: 1.6V to 5.5V
• Improves Low State Noise Margin
• Up to 400kHz Operation
• Auto Detect Low Power Standby Mode
• Low (<5μA) Supply Current Shutdown
• Does Not Load Bus When Disabled or Powered Down
• Strong Slew Limited Pull-up Current
• ±8kV Human Body Model ESD Ruggedness