1027
SAM4CP [DATASHEET]
43051E–ATPL–08/14
Table 45-25
below summarizes recommendations for 32.768 kHz crystal selection.
45.5.10.4 3 to 20 MHz Crystal Oscillator
Notes: 1. See
“Crystal Oscillator Design Considerations Information”
.
2. Rs = 100 - 200
Ω
; Cs = 2.0 - 2.5pF; Cm = 2 - 1.5 fF(typ, worst case) using 1 k
Ω
serial resistor on XOUT.
3. Rs = 50 - 100
Ω
; Cs = 2.0 - 2.5pF; Cm = 4 - 3 fF(typ, worst case).
4. Rs = 25 - 50
Ω
; Cs = 2.5 - 3.0pF; Cm = 7 - 5 fF (typ, worst case).
5. Rs = 20 - 50
Ω
; Cs = 3.2 - 4.0pF; Cm = 10 - 8 fF(typ, worst case).
Table 45-25. Recommended Crystal Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
ESR
Equivalent Series Resistor (R
S
)
Motional capacitance
Crystal @ 32.768 kHz
—
50
100
k
Ω
C
M
C
SHUNT
Crystal @ 32.768 kHz
0.6
—
3
fF
Shunt capacitance
Crystal @ 32.768 kHz
0.6
—
2
pF
Table 45-26. 3 to 20 MHz Crystal Oscillator Characteristics
(1)
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
V
VDDIO
V
VDDPLL
f
OSC
Duty
Supply Voltage Range (VDDIO)
3.0
3.3
3.6
V
Supply Voltage Range (VDDPLL)
1.08
1.2
1.32
V
Operating Frequency range
Normal mode with crystal
3
16
20
MHz
Duty Cycle
40
50
60
%
t
ON
Startup Time
3 MHz, C
SHUNT
= 3pF
8 MHz, C
SHUNT
= 7pF
16 MHz, C
SHUNT
= 7pF with Cm = 8fF
16 MHz, C
SHUNT
= 7pF with Cm = 1.6fF
20 MHz, C
SHUNT
= 7pF
3 MHz
(2)
8 MHz
(3)
16 MHz
(4)
20 MHz
(5)
—
—
14.5
4
1.4
2.5
1
ms
I
DDON
Current consumption
On VDDIO
On VDDPLL
3 MHz
(2)
8 MHz
(3)
16 MHz
(4)
20 MHz
(5)
—
230
300
390
450
6
12
20
24
350
400
470
560
7
14
23
30
μ
A
P
ON
Drive level
3 MHz
8 MHz
16 MHz, 20 MHz
—
—
15
30
50
μ
W
R
f
C
CRYSTAL
C
LEXT
C
LINT
Internal resistor
Between XIN and XOUT
—
0.5
—
M
Ω
Allowed crystal capacitive load
From crystal specification
12
—
18
pF
External capacitor on XIN and XOUT
—
—
—
18
pF
Integrated Load Capacitance
Between XIN and XOUT
7.5
9.5
10.5
pF