Data Sheet

972
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181G–SAM-D21_Datasheet–09/2015
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 36-46. Digital Clock Characteristics
36.11.2.2 Crystal Oscillator Characteristics
Figure 36-6 and the equation in “Crystal Oscillator Characteristics” on page 970 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 36-47. 32kHz Crystal Oscillator Characteristics, Device Variant A
Symbol Parameter Conditions Min. Typ. Max. Units
f
OUT
Crystal oscillator frequency
I
- 32768 - Hz
t
STARTUP
Startup time ESR
XTAL
= 39.9kΩ, 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
C
L
=12.5pF - - 141 kΩ