Freescale Semiconductor, Inc.
General Description
OSC1 and OSC2 Pins
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
of approximately 2 MΩ can be provided between OSC1 and OSC2 for
the ceramic resonator type oscillator by use of the OSCRES bit in the
MOR.
1.7.3 RC Osc illa tor
The lowest cost oscillator is the RC oscillator configuration where a
resistor is connected between the two oscillator pins as shown in Figure
1-3 (b). The internal startup resistor of approximately 2 MΩ is not
recommended between OSC1 and OSC2 for the RC-type oscillator.
The selection of the RC oscillator configuration is done by product part
number selection as described in Section 17. Ordering Information.
1.7.4 Exte rna l Cloc k
An external clock from another CMOS-compatible device can be
connected to the OSC1 input, with the OSC2 input not connected, as
shown in Figure 1-3 (c). This oscillator can be selected via software.
This configuration is possible regardless of whether the crystal/ceramic
resonator or RC oscillator configuration is used.
1.7.5 Inte rna l Low-Powe r Osc illa tor
An internal low-power oscillator (LPO) is provided which is the default
oscillator out of reset. When operating from this internal LPO, the other
oscillator can be powered down by software to further conserve power.
The selection of the LPO configuration is done by product part number
selection as described in Section 17. Ordering Information.
MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0
General Release Specification
General Description
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