Atmel SAM4L Xplained Pro Evaluation Kit Atmel ATSAM4L-XPRO ATSAM4L-XPRO Data Sheet

42023ES–SAM–07/2013

 and the equation above also applies to the 32 kHz oscillator connection. 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 then be found in the crystal datasheet.

Digital Clock Characteristics

f

CPXIN32

XIN32 clock frequency

 (1)

6

MHz

XIN32 clock duty cycle

(1)

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.

32 kHz Crystal Oscillator Characteristics

f

OUT

Crystal oscillator frequency

32 768

Hz

t

STARTUP

Startup time

 (1)

R

m

 = 100k

Ω

, C

L

 = 12.5pF

30000

 (2)

cycles

C

L

Crystal load capacitance

(1)

6

12.5

pF

C

SHUNT

Crystal shunt capacitance

(1)

0.8

1.7

C

XIN

Parasitic capacitor load

 (3)

TQFP100 package

3.4

C

XOUT

Parasitic capacitor load

(3)

2.72

I

OSC32K

Current consumption

(1)

350

nA

ESR

XTAL

Crystal equivalent series 
resistance

(1)

f=32.768kHz

OSCCTRL32.MODE=1

Safety Factor = 3

OSCCTRL32.SELCURR=0

C

L

=6pF

28

k

Ω

OSCCTRL32.SELCURR=4

72

OSCCTRL32.SELCURR=8

114

OSCCTRL32.SELCURR=15

313

OSCCTRL32.SELCURR=0

C

L

=9pF

14

k

Ω

OSCCTRL32.SELCURR=4

36

OSCCTRL32.SELCURR=8

100

OSCCTRL32.SELCURR=15

170

Crystal equivalent series 
resistance

(3)

f=32.768kHz

OSCCTRL32.MODE=1

Safety Factor = 3

OSCCTRL32.SELCURR=4

C

L

=12.5pF

15.2

k

Ω

OSCCTRL32.SELCURR=6

61.8

OSCCTRL32.SELCURR=8

101.8

OSCCTRL32.SELCURR=10

138.5

OSCCTRL32.SELCURR=15

228.5

1.

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

2.

Nominal crystal cycles.

3.

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