SAM4L Datasheet, PDF (1127/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
42.6.2
32kHz Crystal Oscillator (OSC32K) Characteristics
Figure 42-3 and the equation above also applies to the 32kHz 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.
Table 42-21. Digital Clock Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Units
f_CPXIN32
XIN32 clock frequency ⁽¹⁾
XIN32 clock duty cycle⁽¹⁾
6
MHz
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.
Table 42-22. 32 kHz Crystal Oscillator Characteristics
Symbol
Parameter
Conditions
Min Typ
Max Unit
f_OUT
t_STARTUP
C_L
C_SHUNT
C_XIN
C_XOUT
I_OSC32K
Crystal oscillator frequency
Startup time ⁽¹⁾
Crystal load capacitance⁽¹⁾
Crystal shunt capacitance⁽¹⁾
Parasitic capacitor load ⁽³⁾
Parasitic capacitor load⁽³⁾
Current consumption⁽¹⁾
R_m = 100kΩ, C_L = 12.5pF
TQFP100 package
OSCCTRL32.SELCURR=0
32 768
30000 ⁽²⁾
Hz
cycles
6
12.5
0.8
1.7
pF
3.4
2.72
350
nA
28
ESR_XTAL
Crystal equivalent series
resistance⁽¹⁾
f=32.768kHz
OSCCTRL32.MODE=1
Safety Factor = 3
OSCCTRL32.SELCURR=4
OSCCTRL32.SELCURR=8
OSCCTRL32.SELCURR=15
OSCCTRL32.SELCURR=0
OSCCTRL32.SELCURR=4
OSCCTRL32.SELCURR=8
OSCCTRL32.SELCURR=15
C_L=6pF
C_L=9pF
72
kΩ
114
313
14
36
kΩ
100
170
Crystal equivalent series
resistance⁽³⁾
f=32.768kHz
OSCCTRL32.MODE=1
Safety Factor = 3
OSCCTRL32.SELCURR=4
OSCCTRL32.SELCURR=6
OSCCTRL32.SELCURR=8
OSCCTRL32.SELCURR=10
OSCCTRL32.SELCURR=15
C_L=12.5pF
15.2
61.8
101.8 kΩ
138.5
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.
42023C–SAM–02/2013
1127