4.9152 MHz MEMS oscillator — why the resonator matters
The DSC1121AE2-004.9152T is a 4.9152 MHz XO built around a MEMS resonator rather than a quartz crystal — the MEMS die is sealed at wafer level, which gives it shock resistance to 50,000 g and a startup time under 5 ms that a quartz oscillator cannot match. CMOS output at 4.9152 MHz is a standard frequency for UART baud-rate generation, MCU clock inputs, and low-speed serial buses — the ±25 ppm absolute pull range keeps the timing error well under 1 bit period at 115200 baud.