MC68HC705J1ACPE Datasheet, PDF (27/162 Pages) Freescale Semiconductor, Inc – Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.
General Description
Pin Assignments
1.5.2 OSC1 and OSC2
The OSC1 and OSC2 pins are the connections for the on-chip oscillator.
The oscillator can be driven by any of these:
1. Crystal (See Figure 1-4 and Figure 1-5.)
2. Ceramic resonator (See Figure 1-6 and Figure 1-7.)
3. Resistor/capacitor (RC) oscillator (Refer to Appendix A.
MC68HRC705J1A and Appendix C. MC68HSR705J1A.)
4. External clock signal (See Figure 1-8.)
The frequency, f_osc, of the oscillator or external clock source is divided
by two to produce the internal operating frequency, f_op.
1.5.2.1 Crystal Oscillator
Figure 1-4 and Figure 1-5 show 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. An internal startup resistor of approximately
2 MΩ is provided between OSC1 and OSC2 for the crystal oscillator as
a programmable mask option.
NOTE: Use an AT-cut crystal and not an AT-strip crystal because the MCU can
overdrive an AT-strip crystal.
MC68HC705J1A — Rev. 4.0
General Description
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Technical Data