32.12.2.2 Crystal Oscillator Characteristics
Figure 32-6 and the equation in 32.12.1.2 Crystal Oscillator Characteristics also applied to the 32 kHz oscillator connection. The user must choose a crystal oscillator where the crystal load capacitance CL is within the range given in the table. The value of CL can be found in the crystal data sheet.
For the computation of the external capacitors (CLEXT) value, refer to the logic detailed in XOSC Crystal Oscillator Characteristics.
| Symbol | Parameter | Conditions | Min. | Typ. | Max. | Units |
|---|---|---|---|---|---|---|
| fOUT | Crystal oscillator frequency | - | 32768 | - | Hz | |
| tSTARTUP | Startup time | ESRXTAL = 39.9 kΩ, CL = 12.5 pF | - | 28K | 30K | cycles |
| CL | Crystal load capacitance | - | - | 12.5 | pF | |
| CSHUNT | Crystal shunt capacitance | - | 0.1 | - | ||
| CXIN32 | Parasitic capacitor load | - | 3.1 | - | ||
| CXOUT32 | Parasitic capacitor load | - | 3.3 | - | ||
| IXOSC32K | Current consumption | AGC off | - | 1.22 | 2.19 | μA |
| AGC on(1) | - | - | - | |||
| ESR | Crystal equivalent series resistance f = 32.768 kHz Safety Factor = 3 | CL= 12.5 pF | - | - | 141 | kΩ |
Note:
- Refer to the Revision D/Revision C/Revision B errata related to the XOSC32K.