37.13.2.1.1 Crystal Oscillator Characteristics

Figure 37-6 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 data sheet.

Table 37-50. 32kHz Crystal Oscillator Characteristics (Device Variant A)
SymbolParameterConditionsMin.Typ.Max.Units
fOUTCrystal oscillator frequency-32768-Hz
tSTARTUPStartup timeESRXTAL = 39.9 kΩ, CL = 12.5 pF-28K30Kcycles
CLCrystal load capacitance--12.5pF
CSHUNTCrystal shunt capacitance-0.1-
CXIN32Parasitic capacitor load-3.1-
CXOUT32Parasitic capacitor load-3.3-
IXOSC32KCurrent consumption-1.222.19µA
ESRCrystal equivalent series resistance f=32.768kHz
, Safety Factor = 3CL=12.5pF--141kΩ
Table 37-51. 32kHz Crystal Oscillator Characteristics (Device Variant B,C, D, and L)
SymbolParameterConditionsMin.Typ.Max.Units
fOUTCrystal oscillator frequency-32768-Hz
tSTARTUPStartup timeESRXTAL = 39.9 kΩ, CL = 12.5 pF-28K30Kcycles
CLCrystal load capacitance--12.5pF
CSHUNTCrystal shunt capacitance-0.1-
CXIN32Parasitic capacitor load-3.2-
CXOUT32Parasitic capacitor load-3.7-
IXOSC32KCurrent consumption-1.222.19µA
ESRCrystal equivalent series resistance f=32.768kHz
, Safety Factor = 3CL=12.5pF--100kΩ