45.12.2.2 Crystal Oscillator Characteristics

The following table describes the characteristics for the oscillator when a crystal is connected between XIN32 and XOUT32.

The user must choose a crystal oscillator where the crystal load capacitance C_L is within the range given in the table. The exact value of CL can be found in the crystal data sheet. The capacitance of the external capacitors (CLEXT) can then be computed as follows:

C_LEXT=2(C_L-C_STRAY-C_SHUNT)

where C_STRAY is the capacitance of the pins and PCB and C_SHUNT is the shunt capacitance of the crystal.

Table 45-50. 32.768 kHz Crystal Oscillator Characteristics
Symbol	Parameter	Conditions	Min.	Typ.	Max	Units
f_OUT⁽¹⁾	Crystal oscillator frequency		-	32768	-	Hz
C_L⁽¹⁾	Crystal load capacitance		-	-	12.5	pF
C_SHUNT ⁽¹⁾	Crystal shunt capacitance		-	-	1.75	pF
Cm ⁽¹⁾	Motional capacitance		-	1.25	-	fF
ESR	Crystal Equivalent Series Resistance - SF = 3	F = 32.768 kHz, C_L=12.5 pF	-	-	79	kΩ
Cxin32k	Parasitic capacitor load		-	2.9	-	pF
Cxout32k	Parasitic capacitor load		-	3.2	-	pF
Tstart	Startup time	F = 32.768 kHz, C_L=12.5 pF	-	16	24	Kcycles

These are based on simulation. These values are not covered by test or characterization

Table 45-51. Power Consumption⁽¹⁾
Symbol	Parameters	Conditions	Ta	Typ.	Max	Units
I_DD	Current consumption	VDD = 5.0V	Max 85°C Typ 25°C	1528	1720	nA

These are based on characterization.