Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet
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Product codes
ATSAMD21-XPRO
951
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
36.11 Oscillators Characteristics
36.11.1 Crystal Oscillator (XOSC) Characteristics
36.11.1.1 Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied on XIN.
Table 36-36. Digital Clock Characteristics
36.11.1.2 Crystal Oscillator Characteristics
The following table describes the characteristics for the oscillator when a crystal is connected between XIN and XOUT as
shown in
shown in
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.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
f
CPXIN
XIN clock frequency
I
-
-
32
MHz
Table 36-37. Crystal Oscillator Characteristics
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
f
OUT
Crystal oscillator frequency
I
0.4
-
32
MHz
ESR
Crystal Equivalent Series
Resistance
Safety Factor = 3
The AGC doesn’t have any
noticeable impact on these
measurements.
Resistance
Safety Factor = 3
The AGC doesn’t have any
noticeable impact on these
measurements.
f = 0.455MHz, C
L
= 100pF
XOSC.GAIN = 0
-
-
5.6K
Ω
f = 2MHz, C
L
= 20pF
XOSC.GAIN = 0
-
-
416
f = 4MHz, C
L
= 20pF
XOSC.GAIN = 1
-
-
243
f = 8MHz, C
L
= 20pF
XOSC.GAIN = 2
-
-
138
f = 16MHz, C
L
= 20pF
XOSC.GAIN = 3
-
-
66
f = 32MHz, C
L
= 18pF
XOSC.GAIN = 4
-
-
56
C
XIN
Parasitic capacitor load
I
-
5.9
-
pF
C
XOUT
Parasitic capacitor load
-
3.2
-
pF
C
LEXT
2 C
L
C
STRAY
C
SHUNT
–
–
(
)
=