
57
32117DS–AVR-01/12
AT32UC3C
7.6
Oscillator Characteristics
7.6.1
Oscillator (OSC0 and OSC1) Characteristics
7.6.1.1
Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied
on XIN0 or XIN1.
7.6.1.2
Crystal Oscillator Characteristics
The following table describes the characteristics for the oscillator when a crystal is connected
between XIN and XOUT as shown in
Figure 7-2. 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. The capacitance of the external capacitors (C
LEXT) can
then be computed as follows:
where C
PCB is the capacitance of the PCB and Ci is the internal equivalent load capacitance.
Figure 7-2.
Oscillator Connection
Table 7-7.
Digital Clock Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Units
fCPXIN
XIN clock frequency
50
MHz
t
CPXIN
XIN clock period
20
ns
tCHXIN
XIN clock high half-priod
0.4 x tCPXIN
0.6 x tCPXIN
ns
tCLXIN
XIN clock low half-priod
0.4 x tCPXIN
0.6 x tCPXIN
ns
C
IN
XIN input capacitance
2
pF
C
LEXT
2C
L
C
i
–
() C
PCB
–
=
XIN
XOUT
CLEXT
Ci
CL
UC3C