Crystal Oscillator Characteristics

The following table describes the characteristics for the oscillator when a crystal is connected between XIN and XOUT . 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=2CL+−CSTRAY−CSHUNT

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

Table 1. Crystal Oscillator Characteristics (Device Variant A)
Symbol Parameter Conditions Min. Typ. Max. Units
fOUT Crystal oscillator frequency   0.4 - 32 MHz
ESR Crystal Equivalent Series Resistance
Safety Factor = 3

The AGC doesn’t have any noticeable impact on these measurements.

 f = 0.455 MHz, 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 = 8 MHz, CL = 20pF
XOSC.GAIN = 2 - - 138
f = 16 MHz, CL = 20pF
XOSC.GAIN = 3 - - 66
f = 32MHz, CL = 18pF
XOSC.GAIN = 4 - - 56
CXIN Parasitic capacitor load   - 5.9 - pF
CXOUT Parasitic capacitor load   - 3.2 - pF
  Current Consumption f = 2MHz, CL = 20pF, AGC off 27 65 90 μA
f = 2MHz, CL = 20pF, AGC on 14 52 79
f = 4MHz, CL = 20pF, AGC off 61 117 161
f = 4MHz, CL = 20pF, AGC on 23 74 110
f = 8MHz, CL = 20pF, AGC off 131 226 319
f = 8MHz, CL = 20pF, AGC on 56 128 193
f = 16MHz, CL = 20pF, AGC off 305 502 742
f = 16MHz, CL = 20pF, AGC on 116 307 627
f = 32MHz, CL = 18pF, AGC off 1031 1622 2344
f = 32MHz, CL = 18pF, AGC on 278 615 1422
tSTARTUP Start-up time f = 2MHz, CL = 20pF,
XOSC.GAIN = 0, ESR = 600Ω - 14K 48K cycles
f = 4MHz, CL = 20pF,
XOSC.GAIN = 1, ESR = 100Ω - 6800 19.5K
f = 8 MHz, CL = 20pF,
XOSC.GAIN = 2, ESR = 35Ω - 5550 13K
f = 16 MHz, CL = 20pF,
XOSC.GAIN = 3, ESR = 25Ω - 6750 14.5K
f = 32MHz, CL = 18pF,
XOSC.GAIN = 4, ESR = 40Ω - 5.3K 9.6K
Table 2. Crystal Oscillator Characteristics (Device Variant B)
Symbol Parameter Conditions Min. Typ. Max. Units
fOUT Crystal oscillator frequency   0.4 - 32 MHz
ESR Crystal Equivalent Series Resistance
Safety Factor = 3

The AGC doesn’t have any noticeable impact on these measurements.

 f = 0.455 MHz, 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 = 8 MHz, CL = 20pF
XOSC.GAIN = 2 - - 138
f = 16 MHz, CL = 20pF
XOSC.GAIN = 3 - - 66
f = 32MHz, CL = 18pF
XOSC.GAIN = 4 - - 56
CXIN Parasitic capacitor load   - 5.9 - pF
CXOUT Parasitic capacitor load   - 3.2 - pF
  Current Consumption f = 2MHz, CL = 20pF, AGC off 27 65 90 μA
f = 2MHz, CL = 20pF, AGC on 14 52 79
f = 4MHz, CL = 20pF, AGC off 61 117 160
f = 4MHz, CL = 20pF, AGC on 23 74 110
f = 8MHz, CL = 20pF, AGC off 131 226 319
f = 8MHz, CL = 20pF, AGC on 56 128 193
f = 16MHz, CL = 20pF, AGC off 305 502 741
f = 16MHz, CL = 20pF, AGC on 116 307 626
f = 32MHz, CL = 18pF, AGC off 1031 1622 2344
f = 32MHz, CL = 18pF, AGC on 278 615 1400
tSTARTUP Start-up time f = 2MHz, CL = 20pF,
XOSC.GAIN = 0, ESR = 600Ω - 14K 48K cycles
f = 4MHz, CL = 20pF,
XOSC.GAIN = 1, ESR = 100Ω - 6800 19.5K
f = 8 MHz, CL = 20pF,
XOSC.GAIN = 2, ESR = 35Ω - 5550 13K
f = 16 MHz, CL = 20pF,
XOSC.GAIN = 3, ESR = 25Ω - 6750 14.5K
f = 32MHz, CL = 18pF,
XOSC.GAIN = 4, ESR = 40Ω - 5.3K 9.6K
Figure 1. Oscillator Connection
Parent topic: Crystal Oscillator (XOSC) Characteristics