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440 SA-1110 Developer’s Manual
32.768–KHz Oscillator Specifications
The following values are not required for the crystal oscillator to function, but they directly affect
the performance of the oscillator in the system because they determine the accuracy of the crystal
itself. The values given represent those seen on typical crystals used for time keeping, and are
provided for information only.
Specification Minimum Typical Maximum Unit
Resonance Frequency (Fs) — 32768 — Hz
Quality Factor (Q) 40K 80K 200K —
Motional Capacitance (Cm) 234fF
Motional Resistance (Rm) ——50K Ohm
Shunt Capacitance (Co) 0.9 — 2pF
Load Capacitance (Cl) 10 12.5 25 pF
Drive Level ——1 µW
Crystal Type Tuning fork (X+5
o
or X+2
o
cut)
Specification Minimum Typical Maximum Unit
Frequency Tolerance +/-5 +/-20 +/-30 ppm
Parabolic Curvature — -0.042 -0.05 ppm/
o
C
Turnover Temperature 20 25 30
o
C
Temperature Range 0 — 60
o
C
Aging — +/-3 +/-5 ppm/year