Datasheet

723
32133D–11/2011
UC3D
32.7 Oscillator Characteristics
32.7.1 Oscillator 0 (OSC0) Characteristics
32.7.1.1 Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied
on XIN.
32.7.1.2 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 32-2. 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.
Notes: 1. Please refer to the SCIF chapter for details.
Table 32-10. Digital Clock Characteristics
Symbol Parameter Conditions Min Typ Max Units
f
CPXIN
XIN clock frequency 50 MHz
t
CPXIN
XIN clock duty cycle 40 60 %
C
LEXT
2C
L
C
i
–()C
PCB
–=
Table 32-11. Crystal Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
1/(t
CPMAIN
) Crystal oscillator frequency 0.4 20 MHz
C
L
Crystal load capacitance 6 18 pF
C
i
Internal equivalent load capacitance 1.7 pF
t
STARTUP
Startup time
400 KHz Resonator
SCIF.OSCCTRL.GAIN = 0
(1)
198
µs
2 MHz Quartz
SCIF.OSCCTRL.GAIN = 0
(1)
4666
8 MHz Quartz
SCIF.OSCCTRL.GAIN = 1
(1)
975
12 MHz Quartz
SCIF.OSCCTRL.GAIN = 2
(1)
615
16 MHz Quartz
SCIF.OSCCTRL.GAIN = 2
(1)
1106
20 MHz Quartz
SCIF.OSCCTRL.GAIN = 3
(1)
1109