CCU 239 Evacuated Miniature OvenControlled Crystal Oscillator

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Manufacturer: Vectron • Part Number: EX-380-DAF-107A • Package Size: 0.82” x 0.52” x 0.3” • - • An Evacuated Miniature Oven Controlled Crystal Oscillator (EMXO)™ is an improvement on more traditional oven controlled crystal oscillator designs (OCXO). OCXOs use an oven-like environment to provide a constant temperature to the crystal oscillator. Typically, a crystal oscillator’s output frequency can vary significantly over temperature. Maintaining the crystal in a controlled temperature environment keeps the output frequency extremely stable, even as the outside temperature changes. • - • Traditional OCXOs are rather large, and rely on insulation material to separate external temperatures from the internal oven temp. Evacuated Miniature OCXOs improve upon this design by using a vacuum to provide a temperature barrier to the outside environment instead of large amounts of insulation. This allows them to be shrunk way down in size. Power consumption is also decreased, as the internal heating is more efficient. • - • Inside there is a lot to see. There are two layers of ceramic substrates, stacked on top of each other. The crystal is secured underneath what I assume is a gold-plated heating element. The datasheet has a lot of great information about how the 24 step process to create one of these devices, along with diagrams of the internals. I would highly recommend checking it out! • - • https://ww1.microchip.com/downloads/a... • - • https://pdf1.alldatasheet.com/datashe... • - • There are two chips on the lower substrate. The smaller chip is an LMV358, a dual operational amplifier. The larger one is an XC2163T, a chip designed for use with crystal oscillators. It has an interesting array of fuses, some that appear to be blown. These are most likely blown at the factory to select the output frequency divider value.

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