Datasheet

56
9166DS–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 C
i
is the internal equivalent load capacitance.
Figure 7-2. Oscillator Connection
Table 7-7. Digital Clock Characteristics
Symbol Parameter Conditions Min Typ Max Units
f
CPXIN
XIN clock frequency 50 MHz
t
CPXIN
XIN clock period 20 ns
t
CHXIN
XIN clock high half-priod 0.4 x t
CPXIN
0.6 x t
CPXIN
ns
t
CLXIN
XIN clock low half-priod 0.4 x t
CPXIN
0.6 x t
CPXIN
ns
C
IN
XIN input capacitance 2 pF
C
LEXT
2C
L
C
i
–()C
PCB
–=
XIN
XOUT
C
LEXT
C
LEXT
C
i
C
L
UC3C