156.25 MHz LVPECL clock source — MEMS, not quartz
The LVPECL output is a differential signal that drives 50-ohm terminated lines cleanly at this frequency, which is why 156.25 MHz shows up in 10GbE and Fibre Channel reference clocks.
That means the clock edge stays within 25 ppm of 156.25 MHz whether the board is in a freezing cabinet or a hot engine bay — tight enough for most Ethernet and SerDes PLLs to hold lock without re-synchronisation.
Active production — no EOL concern for new designs
Microchip lists the DSC1122BI2-156.2500T as Active. The 6-SMD, No Lead package is a standard 5.0mm x 3.2mm footprint, common enough that a second-source MEMS oscillator from another vendor can fit the same pads if the BOM ever needs a cross.