49.7.13 Main Crystal Oscillator

Table 49-32. Main Crystal Oscillator Characteristics
Symbol	Parameter	Conditions	Min	Max	Unit
V_VDDCORE	Supply voltage (VDDCORE)⁽²⁾	–	V_IT-	⁽³⁾	V
I_VDDCORE	Current consumption (VDDCORE)⁽¹⁾	–	–	500	μA
t_START	Start-up time⁽¹⁾	⁽⁴⁾	–	3	ms
f_OSC	Operating frequency	–	12	48	MHz
Duty	Duty cycle	–	40	60	%
C_PARA	Internal parasitic capacitance⁽¹⁾	Between XIN and XOUT	–	1	pF

Note:

Simulation data.
Functional down to V_IT-of the VDDCORE Supply Monitor.
VDDCORE max.
For all 12 MHz to 48 MHZ crystals complying with the Recommended Crystal Characteristics given in tables Table 49-33, Table 49-34 and Table 49-35.

The oscillator supports a Bypass mode. See Input AC Characteristics.

Figure 49-21. Main Crystal Oscillator Schematic

C_LEXT = 2 × (C_CRYSTAL – C_PARA – C_PCB / 2), where C_PCB is the 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 9 pF load, with C_PCB = 1 pF (on XIN and on XOUT), C_LEXT = 2 x (9 - 1 - 0.5) = 15 pF.

The table below summarizes recommendations for crystal selection. Three sets of crystal characteristics are supported with this oscillator corresponding to the three operating frequency ranges.

Table 49-33. Recommended Crystal Characteristics (Set 1)
Symbol	Parameter	Conditions	Min	Max	Unit
f₀	Fundamental frequency	–	12	24	MHz
C_CRYSTAL	Crystal load capacitance	As specified by the crystal manufacturer	7.5	14.5	pF
ESR	Equivalent Series Resistor (R_S)	–	–	120	Ω
C_SHUNT	Shunt capacitance	–	–	5	pF
P_ON	Drive level	–	40	–	μW

Table 49-34. Recommended Crystal Characteristics (Set 2)
Symbol	Parameter	Conditions	Min	Max	Unit
f₀	Fundamental frequency	–	24	32	MHz
C_CRYSTAL	Crystal load capacitance	As specified by the crystal manufacturer	7.5	9.4	pF
ESR	Equivalent Series Resistor (R_S)	–	–	100	Ω
C_SHUNT	Shunt capacitance	–	–	5	pF
P_ON	Drive level	–	50	–	μW

Table 49-35. Recommended Crystal Characteristics (Set 3)
Symbol	Parameter	Conditions	Min	Max	Unit
f₀	Fundamental frequency	–	32	48	MHz
C_CRYSTAL	Crystal load capacitance	As specified by the crystal manufacturer	4	5.3	pF
ESR	Equivalent Series Resistor (R_S)	–	–	100	Ω
C_SHUNT	Shunt capacitance	–	–	3	pF
P_ON	Drive level	–	50	–	μW