Datasheet

123
42023GS–SAM–03/2014
ATSAM4L8/L4/L2
9.7.2 32kHz Crystal Oscillator (OSC32K) Characteristics
Figure 9-3 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 9-24. Digital Clock Characteristics
Symbol Parameter Conditions Min Typ Max Units
f
CPXIN32
XIN32 clock frequency
(1)
6MHz
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.
Table 9-25. 32 kHz Crystal Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
f
OUT
Crystal oscillator frequency 32 768 Hz
t
STARTUP
Startup time
(1)
R
m
= 100kΩ, C
L
= 12.5pF 30000
(2)
cycles
C
L
Crystal load capacitance
(1)
612.5
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
kΩ
OSCCTRL32.SELCURR=4 72
OSCCTRL32.SELCURR=8 114
OSCCTRL32.SELCURR=15 313
OSCCTRL32.SELCURR=0
C
L
=9pF
14
kΩ
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
kΩ
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.