Freescale Semiconductor, Inc.
General Description
Functional Pin Descriptions
1.6.5 OSC1 a nd OSC2
The OSC1 and OSC2 pins are the connections for the on-chip oscillator.
OSC1 is the input to the oscillator inverter. The output (OSC2) will
always reflect OSC1 inverted except when the device is in stop mode
which forces OSC2 high. The OSC1 and OCS2 pins can accept the
following sets of components:
1. A crystal as shown in Figure 1-3(a)
2. A ceramic resonator as shown in Figure 1-3(a)
3. An external clock signal as shown in Figure 1-3(b)
The frequency, f
, of the oscillator or external clock source is divided
OSC
by two to produce the internal operating frequency, f .
OP
1.6.5.1 Crysta l Osc illa to r
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 and radiated
emissions.
1.6.5.2 Ce ra m ic Re so na to r Osc illa to r
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 and radiated emissions.
MC68HC05V12 — Rev. 1.0
General Release Specification
General Description
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