40.11.2 External 32 kHz Crystal Oscillator (XOSC32K) Characteristics

Digital Clock Characteristics

The following table describes the characteristics for the oscillator when a digital clock is applied on XIN32 pin.

Table 40-46. Digital Clock Characteristics
SymbolParameterConditionsMin.Typ.MaxUnits
fCPXIN32XIN32 clock frequencydigital mode-32.768-kHz
-XIN32 clock duty cycledigital mode-50-%

Crystal Oscillator Characteristics

The figure, Oscillator Connection and the equation in Crystal Oscillator Characteristics 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 40-47. 32 kHz Crystal Oscillator Electrical Characteristics (Device Variant A)
SymbolParameterConditionsMin.Typ.MaxUnits
fOUTCrystal oscillator frequency --32768-Hz
tSTARTUPStartup timeESRXTAL = 39.9 kΩ, CL = 12.5 pF-28K31Kcycles
CLCrystal load capacitance ---12.5pF
CSHUNTCrystal shunt capacitance --0.1-pF
CXIN32Parasitic capacitor loadTQFP64/48/32 packages-3.1-pF
CXOUT32Parasitic capacitor load-3.3-pF
IXOSC32KCurrent consumption --1.22.5µA
ESR

Crystal equivalent series resistance f=32.768kHz

Safety Factor = 3

CL=12.5pF --141kΩ
Table 40-48. 32 kHz Crystal Oscillator Electrical Characteristics (Device Variant B and D)
SymbolParameterConditionsMin.Typ.MaxUnits
fOUTCrystal oscillator frequency --32768-Hz
tSTARTUPStartup timeESRXTAL = 39.9 kW, CL = 12.5 pF-28K31Kcycles
CLCrystal load capacitance ---12.5pF
CSHUNTCrystal shunt capacitance --0.1- -
CXIN32Parasitic capacitor loadTQFP64/48/32 packages-3.2- -
CXOUT32Parasitic capacitor load-3.7- -
IXOSC32KCurrent consumption --1.22.2µA
ESR

Crystal equivalent series resistance f=32.768kHz

Safety Factor = 3

CL=12.5pF --100kΩ