Choosing A Filter - Motorola MC68HC908GP32 Technical Data Manual

7.9.3 Choosing a Filter

MC68HC908GP32 MC68HC08GP32
•
MOTOROLA
Freescale Semiconductor, Inc.
filter capacitor, filter capacitor leakage, stray impedances on the circuit
board, and even humidity or circuit board contamination.
As described in 7.9.2 Parametric Influences on Reaction
external filter network is critical to the stability and reaction time of the
PLL. The PLL is also dependent on reference frequency and supply
voltage.
Either of the filter networks in
a 32.768kHz reference crystal.
requiring better stability.
where stability is not critical.
CGMXFC
10 k Ω
0.033 µ F
Rev. 6
—
Clock Generator Module (CGMC)
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Clock Generator Module (CGMC)
Acquisition/Lock Time Specifications
Figure 7-10 is recommended when using
Figure 7-10
Figure 7-10 (b) is used in low-cost applications
0.01 µ F
V
SSA
(a)
Figure 7-10. PLL Filter
Time, the
(a) is used for applications
CGMXFC
0.47 µ F
V
SSA
(b)
Technical Data
135