Datasheet

56F8367 Technical Data, Rev. 9
40 Freescale Semiconductor
Preliminary
start-up. 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.
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.
Figure 3-3 Connecting a Ceramic Resonator
Note: 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.
3.2.3 External Clock Source
The recommended method of connecting an external clock is given in Figure 3-4. The external clock
source is connected to XTAL and the EXTAL pin is grounded. When using an external clock source, set
R
Z
R
Z
Sample External Crystal Parameters:
R
z
= 750 KΩ
Note: If the operating temperature range is limited to
below 85
o
C (105
o
C junction), then R
z
= 10 Meg Ω
CLKMODE = 0
Crystal Frequency = 4 - 8MHz (optimized for 8MHz)
EXTAL EXTALXTAL XTAL
CL1 CL2
Sample External Ceramic Resonator Parameters:
R
z
= 750 KΩ
Resonator Frequency = 4 - 8MHz (optimized for 8MHz)
3 Terminal
2 Terminal
CLKMODE = 0
CL1 CL2
C1 C2
EXTAL XTALEXTALXTAL
R
Z
R
Z