mc68hc908qz16 Freescale Semiconductor, Inc, mc68hc908qz16 Datasheet - Page 66

• Manufacturer Part Number: mc68hc908qz16
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Clock Generator Module (CGM)
4.3.9 CGM External Connections
In its typical configuration, the CGM requires external components. Five of these are for the crystal
oscillator and two or four are for the PLL.
The crystal oscillator is normally connected in a Pierce oscillator configuration, as shown in
Figure 4-2
circuitry. The oscillator configuration uses five components:
The series resistor (R
crystal manufacturer’s data for more information regarding values for C1 and C2.
Figure 4-2
Routing should be done with great care to minimize signal cross talk and noise.
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•
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Crystal, X
Fixed capacitor, C
Tuning capacitor, C
Feedback resistor, R
Series resistor, R
Bypass capacitor, C
Filter network
shows only the logical representation of the internal components and may not represent actual
also shows the external components for the PLL:
Note: Filter network in box can be replaced with a single capacitor, but will degrade stability.
1
(FROM CONFIG)
OSCSTOPENB
OSC1
C
S
SIMOSCEN
1
) is included in the diagram to follow strict Pierce oscillator guidelines. Refer to the
S
1
X1
2
RB
BYP
B
(can also be a fixed capacitor)
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
Figure 4-2. CGM External Connections
OSC2
RS
C
2
CGMXCLK
3 Component Filter
C
R
F1
F1
CGMXFC
C
F2
V
SSA
Freescale Semiconductor
V
CBYP
0.1 μF
DDA
V
DD
Figure
4-2.