44.12.1.2 Crystal Oscillator Characteristics

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

Figure 44-2. 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. The capacitance of the external capacitors (CLEXT) can then be computed as follows:

CLEXT=2(CL−CSTRAY−CSHUNT)

where CSTRAY is the capacitance of the pins and PCB, CSHUNT is the shunt capacitance of the crystal.

Table 44-36. Crystal Oscillator Characteristics
SymbolParameterConditionsMin.Typ.Max.Units
fOUTCrystal oscillator frequency0.4-32MHz
ESRCrystal Equivalent Series Resistance
Safety Factor=3f=0.455MHz, CL=100pF
 XOSC.GAIN=0--5.6KΩ
f=2MHz, CL=20pF
 XOSC.GAIN=0--416
f=4MHz, CL=20pF
 XOSC.GAIN=1--243
f=8MHz, CL=20pF
 XOSC.GAIN=2--138
f=16MHz, CL=20pF
 XOSC.GAIN=3--66
f=32MHz, CL=20pF
 XOSC.GAIN=4--56
CXINParasitic capacitor load-5.8-pF
CXOUTParasitic capacitor load-3.2-pF
tSTARTUPStart-up timeF=2MHz - CL=20pF XOSC,GAIN=0-14k48kcycles
F=4MHz - CL=20pF XOSC,GAIN=1-6.8k19.5k
F=8MHz - CL=20pF XOSC,GAIN=2-5.6k13k
F=16MHz - CL=20 pF XOSC,GAIN=3-6.8k14.5k
F=32MHz - CL=20pF XOSC,GAIN=4-5.3K9.6k
Note: 1. These values are based on characterization.
Table 44-37. Power consumption
SymbolParameterConditionsTa.Typ.Max.Units
IDDCurrent ConsumptionF=2MHz - CL=20pF XOSC, GAIN=0, VDD =3.3VAGC=OFFMax. 85°C Typ. 25°C89133μA
AGC=ON82130
F=4MHz - CL=20pF XOSC, GAIN=1, VDD =3.3VAGC=OFF140194
AGC=ON102156
F=8MHz - CL=20pF XOSC, GAIN=2, VDD =3.3VAGC=OFF243313
AGC=ON166232
F=16MHz - CL=20pF XOSC, GAIN=3, VDD =3.3VAGC=OFF493605
AGC=ON293393
F=32MHz - CL=20pF XOSC, GAIN=4, VDD =3.3VAGC=OFF14671777
AGC=ON6511045
Note: 1. These values are based on characterization.