mc68hc908ap8cfa Freescale Semiconductor, Inc, mc68hc908ap8cfa Datasheet - Page 96

• Manufacturer Part Number: mc68hc908ap8cfa
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Clock Generator Module (CGM)
Temperature and processing also can affect acquisition time because the electrical characteristics of the
PLL change. The part operates as specified as long as these influences stay within the specified limits.
External factors, however, can cause drastic changes in the operation of the PLL. These factors include
noise injected into the PLL through the filter capacitor, filter capacitor leakage, stray impedances on the
circuit board, and even humidity or circuit board contamination.
6.8.3 Choosing a Filter
As described in
stability and reaction time of the PLL. The PLL is also dependent on reference frequency and supply
voltage.
Either of the filter networks in
(CGMRCLK).
low-cost applications where stability is not critical.
96
Figure 6-10
6.8.2 Parametric Influences on Reaction
(a) is used for applications requiring better stability.
0.22 µF
Figure 6-10
1 kΩ
MC68HC908AP Family Data Sheet, Rev. 4
CGMXFC
(a)
Figure 6-10. PLL Filter
V
is recommended when using a 32.768kHz reference clock
SSA
10 nF
Time, the external filter network is critical to the
CGMXFC
V
SSA
(b)
0.22 µF
Figure 6-10
Freescale Semiconductor
(b) is used in