67.7.6 Main Crystal Oscillator
| Symbol | Parameter | Conditions | Min | Max | Unit |
|---|---|---|---|---|---|
| VDDIN33 | Supply voltage range (VDDIN33)(1) | – | 3.0 | 3.60 | V |
| IDDIN33 | Current consumption (VDDIN33)(2) | – | – | 3.0 | mA |
| tSTART | Start-up time(2) | – | – | 10 | ms |
| fOSC | Operating frequency range | – | 20 | 50 | MHz |
|
Duty |
Duty cycle(2) |
– | 40 | 60 | % |
| CPARA | Internal parasitic capacitance(2) | Between XIN and XOUT | 1 | pF | |
Note:
- This oscillator is powered by the 2.5V regulated output of the VDDOUT25 regulator, which is supplied from VDDIN33.
- Simulation data
The Main crystal oscillator supports a Bypass mode. See Input AC Characteristics.
Two sets of crystal characteristics are supported with this oscillator, corresponding to two operating frequency ranges:
- Set 1: Crystal frequency is between 20 and 30 MHz. See Table 67-40.
- Set 2: Crystal frequency is between 30 and 50 MHz. See Table 67-41.
When choosing a crystal, one and only one of these sets of characteristics must be completely satisfied.
| Symbol | Parameters | Conditions | Min | Max | Unit |
|---|---|---|---|---|---|
| f0 | Fundamental frequency | – | 20 | 30 | MHz |
| CCRYSTAL | Crystal load capacitance | – | 6 | 12.5 | pF |
| RS | Equivalent series resistor | – | – | 100 | Ω |
| CM | Motional capacitance | – | 1.3 | 3 | fF |
| CSHUNT | Shunt capacitance | – | – | 3 | pF |
| PON | Drive level | – | 300 | – | µW |
| Symbol | Parameters | Conditions | Min | Max | Unit |
|---|---|---|---|---|---|
| f0 | Fundamental frequency | – | 30 | 50 | MHz |
| CCRYSTAL | Crystal load capacitance | – | 6 | 10 | pF |
| CSHUNT | Shunt capacitance | With RS_MAX = 60Ω | – | 3 | pF |
|
With RS_MAX = 80Ω |
– |
1 |
pF | ||
| RS | Equivalent series resistor | With CSHUNT_MAX = 1pF | – | 80 | Ω |
| With CSHUNT_MAX = 3pF | – | 60 | Ω | ||
| CM | Motional capacitance | – | 1.3 | 3.2 | fF |
| PON | Drive level | – | 400 | – | µW |
CLEXT = 2 x (CCRYSTAL – CPARA – CPCB / 2).
where CPCB is the single-ended (ground-referenced) parasitic capacitance of the printed circuit board (PCB) on XIN and XOUT tracks. As an example, if the crystal is specified for a 12.5 pF load, with CPCB=1 pF (on XIN and on XOUT), CLEXT = 2 x (12.5 - 1 - 0.5) = 22 pF.