Clock generators are exactly what their name implies, they generate a clock signal. Clock generators are separated into Crystal Oscillators, or XOs, and Voltage Controlled Crystal Oscillators, or VCXOs. VCXOs will be covered in the next slide. Crystal Oscillators are fully integrated devices with no external dependencies, which generate a clock signal. The onsemi Crystal Oscillators are Clock Oscillator Modules that integrate a crystal of a given frequency and a PLL that multiples the frequency of this internal crystal to generate an output frequency that is greater than the frequency of the internal crystal. The crystals that are integrated have a 20 ppm or 50 ppm precision. The internal PLL does not add any multiplication error, so the output frequency will have exactly the same precision as the integrated crystal. The block diagram shown has a pin that is not connected. In some onsemi Crystal Oscillators, that pin is used to choose between 2 possible output frequencies. There is always only a single frequency coming out of the device, but the customer can change the output frequency by toggling this pin in real time. All onsemi XOs have an Output Enable pin that enables and disables the output for low power mode. onsemi XOs are available with LVDS, LVPECL, and CML output levels. onsemi XOs are available with 2.5 V core or 3.3 V core. Some devices can work at both 2.5 V and 3.3 V. These crystal oscillators are available in standard 5 mm x 7 mm packages. XOs in 3.2 mm x 5 mm packages are available as samples.