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:

C LEXT = 2 ( C L − C STRAY − C SHUNT )

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

Table 44-36. Crystal Oscillator Characteristics
Symbol Parameter Conditions Min. Typ. Max. Units
fOUT Crystal oscillator frequency 0.4 - 32 MHz
ESR Crystal Equivalent Series Resistance
Safety Factor=3 f=0.455MHz, CL=100pF
 XOSC.GAIN=0 - - 5.6K Ω
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
CXIN Parasitic capacitor load - 5.8 - pF
CXOUT Parasitic capacitor load - 3.2 - pF
tSTARTUP Start-up time F=2MHz - CL=20pF XOSC,GAIN=0 - 14k 48k cycles
F=4MHz - CL=20pF XOSC,GAIN=1 - 6.8k 19.5k
F=8MHz - CL=20pF XOSC,GAIN=2 - 5.6k 13k
F=16MHz - CL=20 pF XOSC,GAIN=3 - 6.8k 14.5k
F=32MHz - CL=20pF XOSC,GAIN=4 - 5.3K 9.6k
Note: 1. These values are based on characterization.
Table 44-37. Power consumption
Symbol Parameter Conditions Ta. Typ. Max. Units
IDD Current Consumption F=2MHz - CL=20pF XOSC, GAIN=0, VDD =3.3V AGC=OFF Max. 85°C Typ. 25°C 89 133 μA
AGC=ON 82 130
F=4MHz - CL=20pF XOSC, GAIN=1, VDD =3.3V AGC=OFF 140 194
AGC=ON 102 156
F=8MHz - CL=20pF XOSC, GAIN=2, VDD =3.3V AGC=OFF 243 313
AGC=ON 166 232
F=16MHz - CL=20pF XOSC, GAIN=3, VDD =3.3V AGC=OFF 493 605
AGC=ON 293 393
F=32MHz - CL=20pF XOSC, GAIN=4, VDD =3.3V AGC=OFF 1467 1777
AGC=ON 651 1045
Note: 1. These values are based on characterization.