54.13.1 Crystal Oscillator (XOSC) Characteristics

Digital Clock Characteristics

The following table provides the characteristics for the oscillator when a digital clock is applied on XIN.

Table 54-43. Digital Clock Characteristics
Symbol	Parameter	Min.	Typ.	Max.	Units
F_XIN	XIN clock frequency	-	-	48	MHz
DC_XIN (see Note 1)	XIN clock duty cycle	40		60	%

Note:

These values are based on simulation. They are not covered by production test limits or characterization.

Crystal Oscillator Characteristics

The following Table provides 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 C_L is within the range given in the Table. The exact value of C_L can be found in the crystal data sheet. The capacitance of the external capacitors (C_LEXT) can then be computed as follows:

Load Capacitance Equation

C_LOAD = ([C_XIN + C_LEXT] * [C_XOUT + C_LEXT]) / ([C_XIN + C_LEXT + C_LEXT + C_XOUT]) + C_STRAY

Where:

C_LOAD = Crystal Mfg. C_LOAD specification.

C_XIN = XOSC XIN pin data sheet specification.

C_XOUT = XOSC XOUT pin data sheet specification.

C_LEXT = Required external crystal load capacitor.

C_STRAY (Osc PCB capacitance) = 1.5 pf per 12.5 mm (0.5 inches) (TRACE W = 0.175 mm, H = 36 μm, T = 113 μm).

Table 54-44. Multi-Crystal Oscillator Electrical Characteristics ⁽²⁾
Symbol	Parameter	Conditions	Min.	Typ.	Max.	Units
F_OUT	Crystal oscillator frequency		8	-	48	MHz
C_L	Crystal Load	F = 8 MHz	-	-	20	pF
		F = 16 MHz	-	-	20
		F = 32 MHz	-	-	13
		F = 48 MHz	-	-	13
ESR	Crystal Equivalent Series Resistance - SF=3	F = 8 MHz, C_L=20 pF - IMULT = 0x3	-	-	181	Ω
		F = 16 MHz, C_L= 20 pF - IMULT = 0x4	-	-	180
		F= 24 MHz, C_L = 20 pF - IMULT = 0x5	-	-	70
		F = 48 MHz, C_L = 13 pF - IMULT = 0x6	-	-	70
C_XIN	XOSC XIN pin capacitance	-	-	6.3	-	pF
C_XOUT	XOSC XOUT pin capacitance	-	-	5.9	-	pF
D_L	Drive Level ⁽¹⁾	ENALC = ON	-	-	100	μW
Tstart	Startup time	F = 8MHz - CL=20 pF - Cshunt = 2 pF - IMULT=0x3	-	39700	72200	Cycles
		F = 16MHz - CL=20 pF - Cshunt = 1,5 pF - IMULT=0x4	-	37550	62000
		F = 24MHz - CL=20 pF - Cshunt = 2,5 pF - IMULT=0x5	-	32700	68500
		F = 48MHz - CL=13 pF - Cshunt = 5 pF - IMULT=0x6	-	18400	38500

Note:

To ensure that the crystal is not overdriven, the automatic loop control is recommended to be turned ON (ENALC = 1).
Maximum start up time that can be programmed in XOSCCTRL.STARTUP is 1s.

Table 54-45. Power Consumption
Symbol	Parameters	Conditions	TA	Typ.	Max.	Units
I_DD	Current Consumption	F = 8 MHz - C_L = 20 pF - IMULT = 0x3, ENALC = OFF	Max. 85°C, Typ. 25°C	0.43	1.02	mA
		ENALC = ON		0.16	0.66
		F = 16 MHz - C_L = 20 pF - IMULT = 0x5, ENALC = OFF		1.31	2.39
		ENALC = ON		0.25	0.81
		F = 32 MHz - C_L = 13 pF - IMULT = 0x5, ENALC = OFF		2.92	4.75
		ENALC = ON		0.40	1.09
		F = 48 MHz - C_L = 13 pF - IMULT = 0x6, ENALC = OFF		2.70	4.79
		ENALC = ON		0.76	1.46