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Introducing the Si5351A 3 Channel Clock Signal Generator Module, a versatile and high-performance solution for generating frequencies ranging from 8KHz to 160MHz. With its precision 25MHz crystal reference and internal PLL and dividers, this module offers exceptional accuracy and reliability for a wide range of applications.
Whether you're working on RF projects, prototyping with Arduino, or replacing traditional crystal oscillators and PLLs, the Si5351A is your go-to choice. Its I2C interface ensures easy configuration and seamless integration into your projects, making it ideal for cost-sensitive applications requiring precise timing.
Operating at 3-5VDC, this module is designed for easy use with breadboards and can also be connected via an optional SMA connector for more robust setups. The outputs are 3Vpp, providing clear and consistent square wave signals for your needs.
Key Features:
- Generates frequencies from 8KHz to 160MHz with high precision
- Compatible with 3.3V and 5V systems, including Arduino and STM32 platforms
- Easy-to-use I2C interface for flexible configuration
- Ideal for replacing traditional oscillators, VCXOs, and PLLs
- Reliable performance in RF applications and prototyping
bender
Reviewed in the United States on April 15, 2025
This breakout board, featuring the Silicon Labs Si5351A clock generator IC, is a powerful tool for DIY electronics projects requiring precise and multiple clock signals. At its heart, the module utilizes an onboard precision 25MHz crystal reference, coupled with internal Phase-Locked Loops (PLLs) and dividers. This architecture allows it to synthesize three independent square wave clock signals across a remarkably wide frequency range, specified from 8KHz up to 160MHz.Control is handled via the ubiquitous I2C protocol, making it straightforward to interface with common microcontrollers like Arduino, Raspberry Pi, or ESP boards. Adafruit provides an excellent, well-documented Arduino library (Adafruit_Si5351) which is practically indispensable for simplifying the control logic. Their online documentation is also a valuable resource for understanding the chip's capabilities.Configuring the Si5351A to output a specific frequency isn't as simple as just sending a frequency value over I2C. It requires calculating the appropriate settings for the internal PLLs and dividers. While this can be done manually (requiring a grasp of the chip's datasheet) or via spreadsheets, the path of least resistance and highest accuracy is strongly recommended: using the free 'ClockBuilder Pro' desktop application from Skyworks (Silicon Labs). This software provides an intuitive graphical interface (as shown in the helpful screenshots) to determine the necessary register values for desired frequencies, vastly simplifying the setup process.The module offers three independent outputs, each capable of generating a different frequency simultaneously. These outputs deliver a 3V peak-to-peak square wave signal, accessible either through standard 0.1" pin headers or, significantly, via dedicated SMA connectors for improved signal integrity, especially at higher frequencies or in RF applications.My testing involved interfacing the module with an Arduino Uno and utilizing the example code provided within the Adafruit library. Using a modest 10MHz bandwidth oscilloscope, I was able to observe the generated waveforms. They appeared as clean square waves, and modifying frequency parameters within the Arduino sketch resulted in the expected changes on the scope, confirming basic functionality and control.From a hardware perspective, the breakout board itself is of high quality. The PCB is well-made with clear silkscreen labeling for all pins and components, aiding in assembly and connection. Some basic through-hole soldering is required to attach the desired pin headers and the three included SMA connectors. The inclusion of these SMA connectors is a plus, adding considerable value to the package, especially at the reasonable $12.95 price point.Its build quality and included hardware make it a great value for projects ranging from VFOs for radio equipment, custom test signal generation, or providing specific clock signals for digital circuits. And yes, housing it in a classic Altoids tin or a custom 3D-printed enclosure would make for a neat finished project!