46.12.1 Crystal Oscillator (XOSC) Characteristics
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 as shown in the figure 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).
| 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 |
| 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 | |||||