mc68hc908jw32 Freescale Semiconductor, Inc, mc68hc908jw32 Datasheet - Page 63

• Manufacturer Part Number: mc68hc908jw32
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

5.3.9 CGM External Connections
In its typical configuration, the CGMC requires up to nine 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 5-3
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 5-3
Care should be taken with PCB routing in order to minimize signal cross talk and noise. (See
Acquisition/Lock Time Specifications
performance.)
Freescale Semiconductor
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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 0.47μF capacitor, but will degrade stability.
MCU
1
(FROM CONFIG)
OSC_XCLKEN
OSC1
S
C1
SIMOSCEN FROM SIM
) is included in the diagram to follow strict Pierce oscillator guidelines. Refer to the
S
(4-MHZ)
1
2
X1
RB
BYP
B
(can also be a fixed capacitor)
Figure 5-3. CGM External Connections
MC68HC908JW32 Data Sheet, Rev. 5
OSC2
RS
for routing information, filter network and its effects on PLL
C2
CGMXCLK
2n2 F
2kΩ
CGMXFC
100 pF
V
SSPLL
Functional Description
V
DDPLL
CBYP
0.1 μF
Figure
5.8
5-3.
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