40.11.1 Crystal Oscillator (XOSC) Characteristics
| Symbol | Parameter | Conditions | Min. | Typ. | Max | Units |
|---|---|---|---|---|---|---|
| fCPXIN | XIN clock frequency | digital mode | - | - | 32 | MHz |
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 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 = 0.455 MHz, CL = 100pF, XOSC.GAIN = 0 | - | - | 5.6K | Ω |
| f = 2MHz, CL=20 pF XOSC.GAIN=0 | - | - | 330 | |||
| f = 4MHz, CL=20 pF XOSC.GAIN=1 | - | - | 240 | |||
| f = 8MHz, CL=20 pF XOSC.GAIN=2 | - | - | 105 | |||
| f = 16MHz, CL=20 pF XOSC.GAIN=3 | - | - | 60 | |||
| f = 32MHz, CL=18 pF XOSC,GAIN=4 | - | - | 55 | |||
| CXIN | Parasitic load capacitor | - | - | 5.9 | - | pF |
| CXOUT | - | - | 3.2 | - | pF | |
| IXOSC | Current consumption | f = 2MHz, CL=20 pF XOSC.GAIN=0, AGC off | - | 65 | 240 | uA |
| f = 2MHz, CL=20 pF XOSC.GAIN=0, AGC on | - | 52 | 240 | |||
| f = 4MHz, CL=20 pF XOSC.GAIN=1, AGC off | - | 117 | 309 | |||
| f = 4MHz, CL=20 pF XOSC.GAIN=1, AGC on | - | 74 | 281 | |||
| f = 8MHz, CL=20 pF XOSC.GAIN=2, AGC off | - | 226 | 435 | |||
| f = 8MHz, CL=20 pF XOSC.GAIN=2, AGC on | - | 128 | 356 | |||
| f = 16MHz, CL=20 pF XOSC.GAIN=3, AGC off | - | 502 | 748 | |||
| f = 16MHz, CL=20 pF XOSC.GAIN=3, AGC on | - | 307 | 627 | |||
| f = 32MHz, CL=18 pF XOSC.GAIN=4, AGC off | - | 1622 | 2344 | |||
| f = 32MHz, CL=18 pF XOSC.GAIN=4, AGC on | - | 615 | 1422 | |||
| tSTART | Startup time | f = 2MHz, CL=20 pF XOSC,GAIN=0, ESR=600 Ohms | - | 15.6K | 51.0K | Cycles |
| f = 4MHz, CL=20 pF XOSC,GAIN=1, ESR=100 Ohms | - | 6.3K | 20.1K | |||
| f = 8MHz, CL=20 pF XOSC,GAIN=2, ESR=35 Ohms | - | 6.2K | 20.3K | |||
| f = 16MHz, CL=20 pF XOSC,GAIN=3, ESR=25 Ohms | - | 7.7K | 21.2K | |||
| f = 32MHz, CL=18 pF XOSC,GAIN=4, ESR=40 Ohms | - | 6.0K | 14.2K |
