The Adafruit Si5351A Clock Generator with STEMMA QT lets you generate precise, arbitrary clock frequencies from 8 kHz to over 150 MHz using a simple I2C interface. This updated version adds STEMMA QT / Qwiic connectors for solderless hookup alongside the traditional breadboard headers.

With a precision 25 MHz crystal reference and internal PLLs and dividers, it provides three independent outputs, each configurable to a different frequency with 3 Vpp output levels. Output #1 supports an optional edge-launch SMA connector for RF work. Onboard 3.3 V regulation and I2C level shifting allow use with both 3 V and 5 V systems.

Key Features

• Si5351A Clock Generator – I2C-controlled with onboard 25 MHz precision crystal reference
• Wide Frequency Range – 8 kHz to 150+ MHz output
• 3 Independent Outputs – Each output can be set to a different frequency
• 3 Vpp Output – Via header pins; output #1 supports optional edge-launch SMA connector
• STEMMA QT / Qwiic Connectors – Solderless I2C connection and daisy-chaining
• 3–5 V Power – Onboard 3.3 V LDO regulator and level shifting
• Arduino & CircuitPython – Library support for both platforms

Also Consider

• Si5351A Clock Generator Breakout (non-QT) – Original version with SMA connector pads on all three outputs

Ideal For

• Replacing fixed crystals and oscillators in prototypes
• RF and radio projects requiring precise clock signals
• Test and measurement equipment
• Digital signal processing and clock generation

Package Contents

• 1× Adafruit Si5351A Clock Generator with STEMMA QT

Resources

• Adafruit Si5351 Clock Generator Guide & Library