57.4.3 32.768 kHz Crystal Oscillator Characteristics

Symbol Parameter Conditions Min. Typ. Max. Unit
fOSC Operating Frequency Normal mode with crystal 32.77 kHz
tSTART Startup Time 50 800 slow clock cycles 0.9 2.4 s
IDDON Current Consumption ESR < 50 kOhm CCRYSTAL = 12.5 pF 440 680 nA
CCRYSTAL = 6 pF 300 650
ESR < 100 kOhm CCRYSTAL = 12.5 pF 450 650
CCRYSTAL = 6 pF 450 750
CPARA Internal Parasitic Capacitance 0.4 0.5 0.6 pF
Figure 57-9. 32.768 kHz Crystal Oscillator Schematics

CLEXT = 2 × (CCRYSTAL – CPARA – CPCB)

where CPCB is the capacitance of the printed circuit board (PCB) track layout from the crystal to the pin.