Selection reference · illustrative scenario
Define timekeeping before choosing the part
Calendar time, periodic wake-up and device synchronization have different priorities. Define accumulated error, calibration and backup duration before choosing a crystal, clock source or RTC-module architecture.
Engineering: review temperature and power modes
32.768 kHz is not an accuracy grade. Temperature, loading and compensation affect timing; sleep and output behavior affect power. Use the operating profile rather than one typical-current figure.
Procurement: collect functional requirements
State interface, supplies, backup power and time-error target alongside frequency and size. An RTC module and an oscillator cannot be exchanged solely because their frequency matches.
Scenario: room-temperature pass, changing-temperature drift
Compare temperature logs with accumulated timing error and the existing device conditions. If compensation is considered, also review power, software interfaces, calibration and backup switching.
Inquiry & validation checklist
- Timekeeping or wake function
- Accumulated error and temperature
- Battery and backup modes
- Interface and calibration
