Atmel SAM4L-EK Atmel ATSAM4L-EK ATSAM4L-EK Data Sheet

42023E–SAM–07/2013

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

The following table describes the characteristics for the oscillator when a crystal is connected
between XIN and XOUT as shown in 

. 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 datasheet. The capacitance of the external capacitors (C

LEXT

) can

then be computed as follows:

where C

STRAY

 is the capacitance of the pins and PCB, 

C

SHUNT

 is the shunt capacitance of the

crystal.

Table 42-22. Digital Clock Characteristics

f

CPXIN

XIN clock frequency

 (1)

50

MHz

t

CPXIN

XIN clock duty cycle

40

60

%

t

STARTUP

Startup time

N/A

cycles

1.

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

C

LEXT

2 C

L

C

STRAY

C

SHUNT

–

–

(

)

=

Table 42-23. Crystal Oscillator Characteristics

f

OUT

Crystal oscillator frequency

 (1)

0.6

30

MHz

ESR

Crystal Equivalent Series Resistance

 (2)

f = 0.455MHz, C

LEXT

 = 100pF

SCIF.OSCCTRL.GAIN = 0

17000

Ω

f = 2MHz, C

LEXT

 = 20pF

SCIF.OSCCTRL.GAIN = 0

2000

f = 4MHz, C

LEXT

 = 20pF

SCIF.OSCCTRL.GAIN = 1

1500

f = 8MHz, C

LEXT

 = 20pF

SCIF.OSCCTRL.GAIN = 2

300

f = 16MHz, C

LEXT

 = 20pF

SCIF.OSCCTRL.GAIN = 3

350

f = 30MHz, C

LEXT

 = 18pF

SCIF.OSCCTRL.GAIN = 4

45