Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO 数据表
产品代码
ATSAMD21-XPRO
953
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
36.11.2 External 32kHz Crystal Oscillator (XOSC32K) Characteristics
36.11.2.1 Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied on XIN32 pin.
Table 36-38. Digital Clock Characteristics
36.11.2.2 Crystal Oscillator Characteristics
and the equation in
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 be found in the crystal datasheet.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
f
CPXIN32
XIN32 clock frequency
I
-
32.768
-
kHz
I
XIN32 clock duty cycle
I
-
50
-
%
Table 36-39. 32kHz Crystal Oscillator Characteristics
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
f
OUT
Crystal oscillator frequency
I
-
32768
-
Hz
t
STARTUP
Startup time
ESR
XTAL
= 39.9k
Ω, C
L
= 12.5pF
-
28K
30K
cycles
C
L
Crystal load capacitance
I
-
-
12.5
pF
C
SHUNT
Crystal shunt capacitance
I
-
0.1
-
C
XIN32
Parasitic capacitor load
TQFP64/48/32 packages
-
3.1
-
C
XOUT32
Parasitic capacitor load
-
3.3
-
I
XOSC32K
Current consumption
-
1.22
2.19
µA
ESR
Crystal equivalent series
resistance f=32.768kHz
Safety Factor = 3
resistance f=32.768kHz
Safety Factor = 3
C
L
=12.5pF
-
-
141
k
Ω