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参数资料
| 型号： | MC68331CPV20B1 |
| 厂商： | MOTOROLA INC |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | 32-BIT, 20 MHz, MICROCONTROLLER, PQFP144 |
| 封装： | 20 X 20 MM, 1.40 MM HEIGHT, 0.50 MM PITCH, PLASTIC, LQFP-144 |
| 文件页数： | 15/90页 |
| 文件大小： | 481K |
| 代理商： | MC68331CPV20B1 |
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MOTOROLA
MC68331
22
MC68331TS/D
Figure 7 System Clock Block Diagram
3.3.1 Clock Sources
The state of the clock mode (MODCLK) pin during reset determines the clock source. When MODCLK
is held high during reset, the clock synthesizer generates a clock signal from either a crystal oscillator
or an external reference input. Clock synthesizer control register SYNCR determines operating frequen-
cy and various modes of operation. When MODCLK is held low during reset, the clock synthesizer is
disabled, and an external system clock signal must be applied. When the synthesizer is disabled, SYN-
CR control bits have no effect.
A reference crystal must be connected between the EXTAL and XTAL pins to use the internal oscillator.
Use of a 32.768-kHz crystal is recommended. These crystals are inexpensive and readily available. If
an external reference signal or an external system clock signal is applied through the EXTAL pin, the
XTAL pin must be left floating. External reference signal frequency must be less than or equal to max-
imum specified reference frequency. External system clock signal frequency must be less than or equal
to maximum specified system clock frequency.
When an external system clock signal is applied (i.e., the PLL is not used), duty cycle of the input is
critical, especially at near maximum operating frequencies. The relationship between clock signal duty
cycle and clock signal period is expressed:
Minimum external clock period =
minimum external clock high/low time
50% — percentage variation of external clock input duty cycle
SYS CLOCK
BLOCK 32KHZ
CLKOUT
EXTAL
PHASE
COMPARATOR
LOW-PASS
FILTER
VCO
CRYSTAL
OSCILLATOR
SYSTEM
CLOCK
SYSTEM CLOCK CONTROL
XTAL
XFC PIN
VDDSYN
XFC
0.1
F
0.01
F
0.1
F
FEEDBACK DIVIDER
22 pF
10M
330K
1. MUST BE LOW-LEAKAGE CAPACITOR (INSULATION RESISTANCE 30,000 M
OR GREATER).
2. RESISTANCE AND CAPACITANCE BASED ON A TEST CIRCUIT CONSTRUCTED WITH A DAISHINKU DMX-38 32.768-kHz CRYSTAL.
SPECIFIC COMPONENTS MUST BE BASED ON CRYSTAL TYPE. CONTACT CRYSTAL VENDOR FOR EXACT CIRCUIT.
VDDSYN
22
W
X
Y
1
VSSI
R3
R4
32.768 KHz
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| MC68331CPV25 | 制造商:Rochester Electronics LLC 功能描述:32BIT MCU,GPT,SIM,QSM - Bulk |
| MC68331LPV20 | 制造商:Motorola Inc 功能描述: |
| MC68331MEH16 | 功能描述:32位微控制器 - MCU 32B MCU GPT SIM QSM RoHS:否 制造商:Texas Instruments 核心:C28x 处理器系列:TMS320F28x 数据总线宽度:32 bit 最大时钟频率:90 MHz 程序存储器大小:64 KB 数据 RAM 大小:26 KB 片上 ADC:Yes 工作电源电压:2.97 V to 3.63 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:LQFP-80 安装风格:SMD/SMT |
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| MC68331MFC20 | 制造商:MOTOROLA 制造商全称:Motorola, Inc 功能描述:User’s Manual |
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