47.8.1 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 47-28. Digital Clock Characteristics
SymbolParameterMin.Typ.Max.Units
FXINXIN clock frequency--24MHz
DCXINXIN clock duty cycle405060%

Crystal Oscillator Characteristics

The following table describes the characteristics for the oscillator when a crystal is connected between XIN and XOUT as shown in the figure Oscillator Connection.

Figure 47-2. 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 data sheet. The capacitance of the external capacitors (CLEXT) can then be computed as follows:

Load Capacitance Equation

CLOAD = ([CXIN + CLEXT] * [CXOUT + CLEXT]) / ([CXIN + CLEXT + CLEXT + CXOUT]) + CSTRAY

Where:

CLOAD = Crystal Mfg. CLOAD specification

CXIN = XOSC XIN pin data sheet specification

CXOUT = XOSC XOUT pin data sheet specification

CLEXT = Required external crystal load capacitor

CSTRAY (Osc PCB capacitance) = 1.5 pf per 12.5 mm (0.5 inches) (TRACE W = 0.175 mm, H = 36 μm, T = 113 μm)

Table 47-29. Multi Crystal Oscillator Electrical Characteristics
SymbolParameterConditionsMin.Typ.Max.Units
FOUTCrystal oscillator frequency 0.4- 32MHz
ESRCrystal Equivalent Series Resistance - SF=3F=0.4MHz, 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 load capacitor - 5.8- pF
CXOUT - 3.2-
TSTARTStartup timeF=2MHz, CL=20pF XOSC, GAIN=0- 14k48k Cycles
F=4MHz, CL=20pF XOSC, GAIN=1- 6.8k19.5k
F=8MHz, CL=20pF XOSC, GAIN=2- 5.6k13k
F=16MHz, CL=20pF 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 47-30. Power Consumption(1)
SymbolParameterConditionsTaMin.Typ.Max.Units
IDDCurrent consumptionF=2MHz - CL=20pF XOSC,GAIN=0, VCC=3.3V AGC=OFFMax 105°C

Typ 25°C

-89177µA
AGC=ON-82173
F=4MHz - CL=20pF XOSC,GAIN=1, VCC=3.3VAGC=OFF-140242
AGC=ON-102203
F=8MHz - CL=20pF XOSC,GAIN=2, VCC=3.3V AGC=OFF-243365
AGC=ON-166282
F=16MHz - CL=20pF XOSC,GAIN=3, VCC=3.3VAGC=OFF-493669
AGC=ON-293459
F=32MHz - CL=20pF XOSC,GAIN=4, VCC=3.3VAGC=OFF-14671890
AGC=ON-6511080
Note:
  1. These values are based on characterization.