The DSC8121CI5T: It is a blank programmable part — the user must program the output frequency before use, which means ordering a pre-programmed variant or having a programming fixture on hand. The available frequency range is 10 MHz to 100 MHz, covering common reference clocks for MCUs, FPGAs, and Ethernet PHYs.
Supply voltage and output — single-rail flexibility
The CMOS output swings rail-to-rail, which is compatible with most digital logic inputs. That is tight enough for UART bit-rate accuracy, CAN bus, and most serial interfaces without needing a temperature-compensated oscillator.