Load capacitance and ESR — the drive-level pair that matters on the bench
The ECS-270-8-36-RWN-TR: Rated with an 8 pF load capacitance, the crystal expects the MCU or oscillator circuit to present that value across its XTAL pins — a mismatch shifts the actual frequency out of tolerance. The ESR ceiling is 60 Ohms, which sets the maximum drive level the circuit can supply before the crystal risks mechanical degradation; a lower ESR crystal at the same frequency tolerates more drive power from a high-gain oscillator stage.
±15 ppm — what that means inside a timing budget
Frequency tolerance and stability are both ±15 ppm, which stacks directly into the overall timing budget.