MC56F8345 Freescale Semiconductor, Inc, MC56F8345 Datasheet - Page 36

• Manufacturer Part Number: MC56F8345
• Description: 56f8300 16-bit Digital Signal Controllers
• Manufacturer: Freescale Semiconductor, Inc

Part 3 On-Chip Clock Synthesis (OCCS)
3.1 Introduction
Refer to the OCCS chapter of the 56F8300 Peripheral User Manual for a full description of the OCCS.
The material contained here identifies the specific features of the OCCS design.
specific OCCS block diagram to reference in the OCCS chapter of the 56F8300 Peripheral User Manual.
3.2 External Clock Operation
The system clock can be derived from an external crystal, ceramic resonator, or an external system clock
signal. To generate a reference frequency using the internal oscillator, a reference crystal or ceramic
resonator must be connected between the EXTAL and XTAL pins.
3.2.1
The internal oscillator is designed to interface with a parallel-resonant crystal resonator in the frequency
range specified for the external crystal in
in
parameters determine the component values required to provide maximum stability and reliable start-up.
36
Figure
CLKMODE
EXTAL
3-2. Follow the crystal supplier’s recommendations when selecting a crystal, since crystal
XTAL
Crystal Oscillator
Crystal
OSC
Prescaler
÷ (
PLLCID
1,2,4,8
)
Figure 3-1 OCCS Block Diagram
x (1 to 128)
56F8345 Technical Data, Rev. 17
Detector
PLLDB
Lock
PLL
Table
Reference
Detector
Loss of
Clock
F
10-15. A recommended crystal oscillator circuit is shown
OUT
Prescaler CLK
Bus Interface & Control
÷
2
F
OUT/2
PLLCOD
Loss of Reference
÷ (
Postscaler
Clock Interrupt
1,2,4,8
)
LCK
Postscaler CLK
ZSRC
SYS_CLK2
Source to SIM
Figure 3-1
Interface
Freescale Semiconductor
Bus
shows the
Preliminary