This chip has a precision 25MHz crystal reference and internal PLL and dividers
It can generate just about any frequency, from <8KHz up to 160+ MHz.
The Si5351 clock generator is an I2C controller clock generator.
It uses the onboard precision clock to drive multiple PLL's and clock dividers using I2C instructions.
Outputs are 3Vpp, either through a breadboard-friendly header or, for RF work, an optional SMA connector.