67.6.3 32.768 kHz Crystal Oscillator Characteristics

Table 67-22. 32.768 kHz Crystal Oscillator Characteristics
Symbol	Parameter	Conditions		Min	Typ	Max	Unit
f_OSC	Operating Frequency	Normal mode with crystal		–	32.768	–	kHz
t_START	Startup Time	Cm> 3fF		–	–	1200	ms
I_DDON	Current Consumption	ESR < 50k ohm	C_CRYSTAL32 = 12.5 pF	–	440	900	nA
		ESR < 50k ohm	C_CRYSTAL32 = 6 pF		600	900
		ESR < 100k ohm	C_CRYSTAL32 = 12.5 pF		800	1200
		ESR < 100k ohm	C_CRYSTAL32 = 6 pF		700	1200
C_PARA32	Internal Parasitic Capacitance	Between XIN32 and XOUT32		1.4	1.6	1.8	pF

Figure 67-4. 32 kHz Oscillator Schematics

Table 67-23. Recommended 32.768 kHz Crystal Characteristics
Symbol	Parameter	Conditions	Min	Typ	Max	Unit
ESR	Equivalent Series Resistor	Crystal at 32.768 kHz	–	–	100	kΩ
–	Duty Cycle	–	40	50	60	%
C_m	Motional Capacitance	Crystal at 32.768 kHz	3	–	8	fF
C_SHUNT	Shunt Capacitance	Crystal at 32.768 kHz	0.6	–	2	pF
C_CRYSTAL32	Allowed Crystal Capacitance Load(1)	From crystal specification	6	–	12.5	pF
P_ON	Drive Level	–	–	–	0.2	µW

Note: The value of the external capacitors can be determined by using the following formula:

C_LEXT32 = (2 x C_CRYSTAL32) - C_BOARD - (C_PARA32 x 2)

where:

C_LEXT32 is the external capacitor value which must be soldered from XIN to GND and XOUT to GND
C_CRYSTAL32 is crystal targeted load
C_BOARD is the external board parasitic capacitance (from XIN to GND or XOUT to GND)
C_PARA32 is the internal parasitic capacitance

SAMA5D29