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| 型号： | PIC17C44 |
| 元件分类： | 外设及接口 |
| 英文描述： | Low Power 5V RS232 Dual Driver/Receiver with 0.1?μF Capacitors; Package: SO; No of Pins: 16; Temperature Range: -40?°C to 85?°C |
| 中文描述： | 电可擦除可编程逻辑器件 |
| 文件页数： | 7/71页 |
| 文件大小： | 1173K |
| 代理商： | PIC17C44 |
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1996 Microchip Technology Inc.
DS30412C-page 15
PIC17C4X
4.0
RESET
The PIC17CXX differentiates between various kinds of
reset:
Power-on Reset (POR)
MCLR reset during normal operation
WDT Reset (normal operation)
Some registers are not affected in any reset condition;
their status is unknown on POR and unchanged in any
other reset. Most other registers are forced to a “reset
state” on Power-on Reset (POR), on MCLR or WDT
Reset and on MCLR reset during SLEEP. They are not
affected by a WDT Reset during SLEEP, since this reset
is viewed as the resumption of normal operation. The
TO and PD bits are set or cleared differently in different
reset situations as indicated in Table 4-3. These bits are
used in software to determine the nature of reset. See
Table 4-4 for a full description of reset states of all reg-
isters.
A simplied block diagram of the on-chip reset circuit is
shown in Figure 4-1.
Note:
While the device is in a reset state, the
internal phase clock is held in the Q1 state.
Any processor mode that allows external
execution will force the RE0/ALE pin as a
low output and the RE1/OE and RE2/WR
pins as high outputs.
4.1
Power-on Reset (POR), Power-up
Timer (PWRT), and Oscillator Start-up
Timer (OST)
4.1.1
POWER-ON RESET (POR)
The Power-on Reset circuit holds the device in reset
until VDD is above the trip point (in the range of 1.4V -
2.3V). The PIC17C42 does not produce an internal
reset when VDD declines. All other devices will produce
an internal reset for both rising and falling VDD. To take
advantage of the POR, just tie the MCLR/VPP pin
directly (or through a resistor) to VDD. This will eliminate
external RC components usually needed to create
Power-on Reset. A minimum rise time for VDD is
required. See Electrical Specications for details.
4.1.2
POWER-UP TIMER (PWRT)
The Power-up Timer provides a xed 96 ms time-out
(nominal) on power-up. This occurs from rising edge of
the POR signal and after the rst rising edge of MCLR
(detected high). The Power-up Timer operates on an
internal RC oscillator. The chip is kept in RESET as
long as the PWRT is active. In most cases the PWRT
delay allows the VDD to rise to an acceptable level.
The power-up time delay will vary from chip to chip and
to VDD and temperature. See DC parameters for
details.
FIGURE 4-1:
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
S
R
Q
External
Reset
MCLR
VDD
OSC1
WDT
Module
VDD rise
detect
OST/PWRT
On-chip
RC OSC
WDT
Time_Out
Power_On_Reset
OST
10-bit Ripple counter
PWRT
Chip_Reset
10-bit Ripple counter
Power_Up
(Enable the PWRT timer
only during Power_Up)
(Power_Up + Wake_Up) (XT + LF)
(Enable the OST if it is Power_Up or Wake_Up
from SLEEP and OSC type is XT or LF)
Reset
Enab
le
OST
Enab
le
PWR
T
This RC oscillator is shared with the WDT
when not in a power-up sequence.
This document was created with FrameMaker404
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| PIC17C44/JW | 功能描述:8位微控制器 -MCU 16KB 454 RAM 33 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 |
| PIC17C44-16/L | 功能描述:8位微控制器 -MCU 16KB 454 RAM 33 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 |
| PIC17C44-16/P | 功能描述:8位微控制器 -MCU 16KB 454 RAM 33 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 |
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| PIC17C44-16/PQ | 功能描述:8位微控制器 -MCU 16KB 454 RAM 33 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 |
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