56F8366_09 Datasheet, PDF (39/182 Pages) Freescale Semiconductor, Inc – 16-bit Digital Signal Controllers

External Clock Operation
The crystal and associated components should be mounted as near as possible to the EXTAL and XTAL
pins to minimize output distortion and start-up stabilization time.
Crystal Frequency = 4 - 8MHz (optimized for 8MHz)
EXTAL XTAL EXTAL XTAL
R_z
R_z
Sample External Crystal Parameters:
R_z = 750 KΩ
CLKMODE = 0
Note: If the operating temperature range is limited to
below 85^oC (105^oC junction), then R_z = 10 Meg Ω
CL1
CL2
Figure 3-2 Connecting to a Crystal Oscillator
Note:
The OCCS_COHL bit must be set to 1 when a crystal oscillator is used. The reset condition on the
OCCS_COHL bit is 0. Please see the COHL bit in the Oscillator Control (OSCTL) register, discussed
in the 56F8300 Peripheral User Manual.
3.2.2 Ceramic Resonator (Default)
It is also possible to drive the internal oscillator with a ceramic resonator, assuming the overall system
design can tolerate the reduced signal integrity. A typical ceramic resonator circuit is shown in Figure 3-3.
Refer to the supplier’s recommendations when selecting a ceramic resonator and associated components.
The resonator and components should be mounted as near as possible to the EXTAL and XTAL pins.
Resonator Frequency = 4 - 8MHz (optimized for 8MHz)
2 Terminal
EXTAL XTAL
R_z
3 Terminal
EXTAL XTAL
R_z
Sample External Ceramic Resonator Parameters:
R_z = 750 KΩ
CL1
CL2
C1
C2
CLKMODE = 0
Note:
Figure 3-3 Connecting a Ceramic Resonator
The OCCS_COHL bit must be set to 0 when a ceramic resonator is used. The reset condition on the
OCCS_COHL bit is 0. Please see the COHL bit in the Oscillator Control (OSCTL) register, discussed
in the 56F8300 Peripheral User Manual.
56F8366 Technical Data, Rev. 7
Freescale Semiconductor
39
Preliminary