mc68hc705j2 Freescale Semiconductor, Inc, mc68hc705j2 Datasheet - Page 13

• Manufacturer Part Number: mc68hc705j2
• Description: 8-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

2.2.1 Crystal
2.2.2 Ceramic Resonator
2.1 V
2.2 OSC1 and OSC2
MOTOROLA
2-2
D D
V
single 5-V power supply.
Very fast signal transitions occur on the MCU pins. The short rise and fall times
place very high short-duration current demands on the power supply.
prevent noise problems, take special care to provide good power supply
bypassing at the MCU.
characteristics, and position them as close to the MCU as possible. Bypassing
requirements vary, depending on how heavily loaded the MCU pins are.
The OSC1 and OSC2 pins are the control connections for the on-chip oscillator.
Connect any of the following to the OSC1 and OSC2 pins:
The MCU divides the frequency, f osc , of the oscillator or external clock source
by two to produce the internal operating frequency, f op .
The circuit in Figure 2-2 shows a typical crystal oscillator circuit for a parallel
resonant crystal. Follow the crystal supplier's recommendations, as the crystal
parameters determine the external component values required to provide
maximum stability and reliable start-up. The load capacitance values used in
the oscillator circuit design should include all stray layout capacitances. Mount
the crystal and components as close as possible to the pins for start-up
stabilization and to minimize output distortion.
In cost-sensitive applications, use a ceramic resonator in place of the crystal.
Use the circuit in Figure 2-2 for a ceramic resonator, and follow the resonator
manufacturer's recommendations, 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 layout capacitances.
DD
• A crystal (Refer to Figure 2-2.)
• A ceramic resonator (Refer to Figure 2-2.)
• An external clock signal (Refer to Figure 2-3.)
and V
and V
S S
SS
are the power supply and ground pins. The MCU operates from a
PIN DESCRIPTIONS
Use bypass capacitors with good high-frequency
MC68HC705J2
To