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参数资料
型号： PIC18LF4431-I/PT
厂商： Microchip Technology
文件页数： 66/119页
文件大小： 0K
描述： IC PIC MCU FLASH 8KX16 44TQFP
产品培训模块： Asynchronous Stimulus
8-bit PIC® Microcontroller Portfolio
标准包装： 160
系列： PIC® 18F
核心处理器： PIC
芯体尺寸： 8-位
速度： 40MHz
连通性： I²C，SPI，UART/USART
外围设备： 欠压检测/复位，LVD，电源控制 PWM，QEI，POR，PWM，WDT
输入/输出数： 36
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)： 2 V ~ 5.5 V
数据转换器： A/D 9x10b
振荡器型： 内部
工作温度： -40°C ~ 85°C
封装/外壳： 44-TQFP
包装： 托盘
产品目录页面： 645 (CN2011-ZH PDF)
PIC18F2331/2431/4331/4431
DS39616D-page 50
2010 Microchip Technology Inc.
5.5
Device Reset Timers
PIC18F2331/2431/4331/4431
devices
incorporate
three separate on-chip timers that help regulate the
Power-on Reset process. Their main function is to
ensure that the device clock is stable before code is
executed. These timers are:
Power-up Timer (PWRT)
Oscillator Start-up Timer (OST)
PLL Lock Time-out
5.5.1
POWER-UP TIMER (PWRT)
The Power-up Timer (PWRT) of PIC18F2331/2431/
4331/4431 devices is an 11-bit counter that uses the
INTRC source as the clock input. This yields an
approximate time interval of 2,048 x 32
s = 65.6 ms.
While the PWRT is counting, the device is held in
Reset. The power-up time delay depends on the
INTRC clock and will vary from chip to chip due to tem-
perature and process variation. See DC Parameter 33
for details.
The PWRT is enabled by clearing the PWRTEN
Configuration bit.
5.5.2
OSCILLATOR START-UP TIMER
(OST)
The Oscillator Start-up Timer (OST) provides a
1,024 oscillator cycle (from OSC1 input) delay after the
PWRT delay is over (Parameter 33). This ensures that
the crystal oscillator or resonator has started and
stabilized.
The OST time-out is invoked only for XT, LP, HS and
HSPLL modes, and on Power-on Reset or on exit from
most power-managed modes.
5.5.3
PLL LOCK TIME-OUT
With the PLL enabled in its PLL mode, the time-out
sequence following a Power-on Reset is slightly differ-
ent from other oscillator modes. A separate timer is
used to provide a fixed time-out that is sufficient for the
PLL to lock to the main oscillator frequency. This PLL
Lock Time-out (TPLL) is typically 2 ms and follows the
oscillator start-up time-out.
5.5.4
TIME-OUT SEQUENCE
On power-up, the time-out sequence is as follows:
1.
After the POR pulse has cleared, the PWRT time-out
is invoked (if enabled).
2.
Then, the OST is activated.
The total time-out will vary based on oscillator configu-
ration and the status of the PWRT. Figure 5-3 through
Figure 5-7 depict time-out sequences on power-up,
with the Power-up Timer enabled and the device oper-
ating in HS Oscillator mode. Figure 5-3 through
Figure 5-6 also apply to devices operating in XT or LP
modes.
For devices in RC mode, and with the PWRT disabled,
there will be no time-out at all. Since the time-outs
occur from the POR pulse, if MCLR is kept low long
enough, all time-outs will expire. Bringing MCLR high
will begin execution immediately (Figure 5-5). This is
useful for testing purposes or synchronization of more
than one PIC18FXXXX device operating in parallel.
TABLE 5-1:
TIME-OUT IN VARIOUS SITUATIONS
Oscillator
Configuration
Power-up(2) and Brown-out
Exit From
Power-Managed Mode
PWRTEN = 0
PWRTEN = 1
HSPLL
66 ms(1) + 1024 TOSC + 2 ms(2)
1024 TOSC + 2 ms(2)
HS, XT, LP
66 ms(1) + 1024 TOSC
1024 TOSC
EC, ECIO
66 ms(1)
——
RC, RCIO
66 ms(1)
——
INTIO1, INTIO2
66 ms(1)
——
Note 1:
66 ms (65.5 ms) is the nominal Power-up Timer (PWRT) delay.
2:
2 ms is the nominal time required for the 4x PLL to lock.
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相关代理商/技术参数
参数描述
PIC18LF4431T-I/ML 功能描述:8位微控制器 -MCU 16KB 768 RAM 34I/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
PIC18LF4431T-I/PT 功能描述:8位微控制器 -MCU 16KB 768 RAM 34I/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
PIC18LF4439-I/ML 功能描述:8位微控制器 -MCU 12KB 640 RAM 32I/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
PIC18LF4439-I/P 功能描述:8位微控制器 -MCU 12KB 640 RAM 32I/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
PIC18LF4439-I/PT 功能描述:8位微控制器 -MCU 12KB 640 RAM 32I/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
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