AB26TRQ-32.768KHz-T Crystal

32.768kHz is not a random number, it's exactly 2 to the 15th power, which lets a simple binary counter divide this crystal's oscillation down to a precise one-second tick with nothing more than a chain of flip-flops. That's exactly why real-time clock chips like the DS3231 already in the catalog are built around a crystal at this frequency, and this AB26TRQ part supplies it for a design building its own timekeeping circuit rather than relying on an all-in-one RTC module.