MC68HC705P9 Datasheet, PDF (27/160 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Pin Descriptions
Pin Functions
2.3.2 OSC1 and OSC2
The OSC1 and OSC2 pins are the connections for the on-chip oscillator.
The oscillator can be driven by any of the following:
• Crystal
• Ceramic resonator
• External clock signal
The frequency of the on-chip oscillator is f_OSC. The MCU divides the
internal oscillator output by two to produce the internal clock with a
frequency of f_OP.
2.3.2.1 Crystal Connections
The circuit in Figure 2-3 shows a
typical crystal oscillator circuit
for an AT-cut, parallel resonant
crystal. Follow the crystal
supplier’s recommendations, as
the crystal parameters
determine the external
component values required to
provide reliable startup and
maximum stability. The load
capacitance values used in the
oscillator circuit design should
include all stray layout
capacitances. To minimize
output distortion, mount the
crystal and capacitors as close
as possible to the pins.
MCU
10 MΩ
XTAL
27 pF
27 pF
Figure 2-3. Crystal Connections
NOTE:
Use an AT-cut crystal. Do not use a strip or tuning fork crystal. The MCU
may overdrive or have the incorrect characteristic impedance for a strip
or tuning fork crystal.
MC68HC705P9 — Rev. 4.0
MOTOROLA
Pin Descriptions
For More Information On This Product,
Go to: www.freescale.com
Technical Data
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