参数资料
型号: PIC18F448-E/P
厂商: Microchip Technology
文件页数: 24/116页
文件大小: 0K
描述: IC MCU FLASH 8KX16 W/CAN 40-DIP
产品培训模块: Asynchronous Stimulus
标准包装: 10
系列: PIC® 18F
核心处理器: PIC
芯体尺寸: 8-位
速度: 40MHz
连通性: CAN,I²C,SPI,UART/USART
外围设备: 欠压检测/复位,LVD,POR,PWM,WDT
输入/输出数: 33
程序存储器容量: 16KB(8K x 16)
程序存储器类型: 闪存
EEPROM 大小: 256 x 8
RAM 容量: 768 x 8
电压 - 电源 (Vcc/Vdd): 4.2 V ~ 5.5 V
数据转换器: A/D 8x10b
振荡器型: 外部
工作温度: -40°C ~ 125°C
封装/外壳: 40-DIP(0.600",15.24mm)
包装: 管件
2006 Microchip Technology Inc.
DS41159E-page 21
PIC18FXX8
2.6.2
OSCILLATOR TRANSITIONS
The PIC18FXX8 devices contain circuitry to prevent
“glitches” when switching between oscillator sources.
Essentially, the circuitry waits for eight rising edges of
the clock source that the processor is switching to. This
ensures that the new clock source is stable and that its
pulse width will not be less than the shortest pulse
width of the two clock sources.
Figure 2-7 shows a timing diagram indicating the tran-
sition from the main oscillator to the Timer1 oscillator.
The Timer1 oscillator is assumed to be running all the
time. After the SCS bit is set, the processor is frozen at
the next occurring Q1 cycle. After eight synchronization
cycles
are
counted
from
the
Timer1
oscillator,
operation resumes. No additional delays are required
after the synchronization cycles.
The sequence of events that takes place when switch-
ing from the Timer1 oscillator to the main oscillator will
depend on the mode of the main oscillator. In addition
to eight clock cycles of the main oscillator, additional
delays may take place.
If the main oscillator is configured for an external
crystal (HS, XT, LP), the transition will take place after
an oscillator start-up time (TOST) has occurred. A timing
diagram indicating the transition from the Timer1
oscillator to the main oscillator for HS, XT and LP
modes is shown in Figure 2-8.
FIGURE 2-7:
TIMING DIAGRAM FOR TRANSITION FROM OSC1 TO TIMER1 OSCILLATOR
FIGURE 2-8:
TIMING DIAGRAM FOR TRANSITION BETWEEN TIMER1 AND OSC1 (HS, XT, LP)
Q3
Q2
Q1
Q4
Q3
Q2
OSC1
Internal
SCS
(OSCCON<0>)
Program
PC + 2
PC
Note 1: Delay on internal system clock is eight oscillator cycles for synchronization.
Q1
T1OSI
Q4
Q1
PC + 4
Q1
Tscs
Clock
Counter
System
Q2
Q3
Q4
Q1
TDLY
TT1P
TOSC
2
13
4
5
6
7
8
Q3
Q4
Q1 Q2 Q3 Q4
Q1 Q2
OSC1
Internal System
SCS
(OSCCON<0>)
Program
PC
PC + 2
Note 1: TOST = 1024 TOSC (drawing not to scale).
T1OSI
Clock
OSC2
TOST
Q1
PC + 4
TT1P
TOSC
TSCS
12
3
4
5
6
7
8
Counter
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PIC18F448-I/L 功能描述:8位微控制器 -MCU 16KB 768 RAM 34 I/O RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC18F448-I/L 制造商:Microchip Technology Inc 功能描述:IC 8BIT FLASH MCU CAN ADC 18F448
PIC18F448-I/P 功能描述:8位微控制器 -MCU 16KB 768 RAM 34 I/O RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC18F448-I/P 制造商:Microchip Technology Inc 功能描述:IC 8BIT FLASH MCU CAN ADC 18F448
PIC18F448-I/PT 功能描述:8位微控制器 -MCU 16KB 768 RAM 34 I/O RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT