MEMS resonator, blank-programmable clock source
The DSC8121BI2T: Unlike quartz-based oscillators, the MEMS resonator structure is inherently more resistant to vibration and shock, and the blank-programmable nature means the part ships without a pre-set frequency — you program it to your exact target using Microchip's TimeFlash or field-programmer tools, which is useful for prototype runs or low-volume production where stocking multiple pre-programmed frequencies is impractical.
Stability, temperature, and supply tolerance
For a 100 MHz carrier, ±25 ppm translates to a maximum frequency error of ±2.5 kHz — tight enough for most UART, SPI, and Ethernet clocking applications, but not tight enough for precision timing like IEEE 1588 or GPS holdover, where ±10 ppm or better is typical.