MC68HC705JP7 Datasheet, PDF (30/242 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
General Description
MCU
2 MΩ
OSC1
OSC2
MCU
OSC1
R
OSC2
MCU
OSC1
OSC2
UNCONNECTED
(a) Crystal or
Ceramic Resonator
Connections
(b) RC Oscillator
Connections
EXTERNAL CLOCK
(c) External Clock
Source Connection
Figure 1-3. EPO Oscillator Connections
1.7.1 Crystal Oscillator
The circuit in Figure 1-3 (a) shows a typical oscillator circuit for an
AT-cut, parallel resonant crystal. The crystal manufacturer’s
recommendations should be followed, as the crystal parameters
determine the external component values required to provide maximum
stability and reliable startup. The load capacitance values used in the
oscillator circuit design should include all stray capacitances. The crystal
and components should be mounted as close as possible to the pins for
startup stabilization and to minimize output distortion. An internal startup
resistor of approximately 2 MΩ can be provided between OSC1 and
OSC2 for the crystal type oscillator by use of the OSCRES bit in the
MOR.
1.7.2 Ceramic Resonator Oscillator
In cost-sensitive applications, a ceramic resonator can be used in place
of the crystal. The circuit in Figure 1-3 (a) can be used for a ceramic
resonator. The resonator manufacturer’s recommendations should be
followed, as the resonator parameters determine the external
component values required for maximum stability and reliable starting.
The load capacitance values used in the oscillator circuit design should
include all stray capacitances. The ceramic resonator and components
should be mounted as close as possible to the pins for startup
stabilization and to minimize output distortion. An internal startup resistor
Advance Information
30
MC68HC705JJ7 • MC68HC705JP7 — REV 4
General Description
For More Information On This Product,
Go to: www.freescale.com
MOTOROLA