Crystal Oscillator Characteristics

Figure 1 and the equation in also applies 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 exact value of CL can be found in the crystal datasheet.

Table 1. 32kHz Crystal Oscillator Characteristics (Device Variant A)
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   - 1.22 2.19 µA
ESR Crystal equivalent series resistance f=32.768kHz
, Safety Factor = 3 CL=12.5pF - - 141 kΩ
Table 2. 32kHz Crystal Oscillator Characteristics (Device Variant B)
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   - 3.2 -
CXOUT32 Parasitic capacitor load   - 3.7 -
IXOSC32K Current consumption   - 1.22 2.19 µA
ESR Crystal equivalent series resistance f=32.768kHz
, Safety Factor = 3 CL=12.5pF - - 100 kΩ
Parent topic: Digital Clock Characteristics