参数资料
型号: MC68HC705C8ACP
厂商: MOTOROLA INC
元件分类: 微控制器/微处理器
英文描述: HCMOS Microcontroller Unit
中文描述: 8-BIT, OTPROM, 2.1 MHz, MICROCONTROLLER, PDIP40
封装: PLASTIC, DIP-40
文件页数: 16/108页
文件大小: 718K
代理商: MC68HC705C8ACP
Introduction
MC68HC705KJ1 MC68HRC705KJ1 MC68HLC705KJ1 Data Sheet, Rev. 4.1
16
Freescale Semiconductor
1.4.1 V
DD
and V
SS
V
DD
and V
SS
are the power supply and ground pins. The MCU operates from a single power supply.
Very fast signal transitions occur on the MCU pins, placing high, short-duration current demands on the
power supply. To prevent noise problems, take special care, as
Figure 1-3
shows, by placing the bypass
capacitors as close as possible to the MCU. C2 is an optional bulk current bypass capacitor for use in
applications that require the port pins to source high current levels.
Figure 1-3. Bypassing Layout Recommendation
1.4.2 OSC1 and OSC2
The OSC1 and OSC2 pins are the connections for the on-chip oscillator. The oscillator can be driven by
any of the following:
1.
Standard 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 MC68HRC705KJ1
.)
4.
External clock signal as shown in (See
Figure 1-8
.)
5.
Low speed (32 kHz) crystal connections (Refer to
Appendix B MC68HLC705KJ1
.)
The frequency, f
OSC
, of the oscillator or external clock source is divided by two to produce the internal
operating frequency, f
OP
.
1.4.2.1 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 M
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.
C1
C2
MCU
C1
0.1
μ
F
C2
V+
+
V
DD
V
SS
V
DD
V
SS
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MC68HC705C8ACPE 制造商:Freescale Semiconductor 功能描述:
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MC68HC705C8AVFB 制造商:Rochester Electronics LLC 功能描述:- Bulk