15.12.1 Crystal Oscillator (XOSC) Characteristics

Digital Clock Characteristics

The following table describes the characteristics for the oscillator when a digital clock is applied on XIN.
Table 15-33. Digital Clock Characteristics
Symbol Parameter Min. Typ. Max. Units
FXIN XIN clock frequency - - 24 MHz
DCXIN XIN clock duty cycle 40 50 60 %

Crystal Oscillator Characteristics

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

Figure 15-3. 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 - SHUNT) ,

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

Table 15-34. Multi Crystal Oscillator Electrical Characteristics
Symbol Parameter Conditions Min. Typ. Max. Units
FOUT Crystal oscillator frequency 0.4 - 32 MHz
ESR Crystal Equivalent Series Resistance - SF=3 F=0.4MHz, 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 load capacitor - 5.8 - pF
CXOUT - 3.2 -
TSTART Startup 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=20pF 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 15-35. Power Consumption(1)
Symbol Parameter Conditions Ta Min. Typ. Max. Units
IDD Current consumption F=2MHz - CL=20pF XOSC,GAIN=0, VCC=3.3V AGC=OFF Max 85°C

Typ 25°C

 - 89 133 µA
AGC=ON - 82 130
F=4MHz - CL=20pF XOSC,GAIN=1, VCC=3.3V AGC=OFF - 140 194
AGC=ON - 102 156
F=8MHz - CL=20pF XOSC,GAIN=2, VCC=3.3V AGC=OFF - 243 313
AGC=ON - 166 232
F=16MHz - CL=20pF XOSC,GAIN=3, VCC=3.3V AGC=OFF - 493 605
AGC=ON - 293 393
F=32MHz - CL=20pF XOSC,GAIN=4, VCC=3.3V AGC=OFF - 1467 1777
AGC=ON - 651 1045
Note: (1) These values are based on characterization.