| 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 1. 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.