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PIC18LF6720-I/PT 参数 Datasheet PDF下载

PIC18LF6720-I/PT图片预览
型号: PIC18LF6720-I/PT
PDF下载: 下载PDF文件 查看货源
内容描述: 八十〇分之六十四引脚高性能1 Mbit的增强型闪存微控制器与A / D [64/80-Pin High Performance 1 Mbit Enhanced FLASH Microcontrollers with A/D]
分类和应用: 闪存微控制器
文件页数/大小: 366 页 / 6797 K
品牌: MICROCHIP [ MICROCHIP ]
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PIC18FXX20  
The following steps are needed to set up the LVD  
module:  
1. Write the value to the LVDL3:LVDL0 bits  
(LVDCON register), which selects the desired  
LVD Trip Point.  
22.2 Operation  
Depending on the power source for the device voltage,  
the voltage normally decreases relatively slowly. This  
means that the LVD module does not need to be con-  
stantly operating. To decrease the current require-  
ments, the LVD circuitry only needs to be enabled for  
short periods, where the voltage is checked. After  
doing the check, the LVD module may be disabled.  
Each time that the LVD module is enabled, the circuitry  
requires some time to stabilize. After the circuitry has  
stabilized, all status flags may be cleared. The module  
will then indicate the proper state of the system.  
2. Ensure that LVD interrupts are disabled (the  
LVDIE bit is cleared or the GIE bit is cleared).  
3. Enable the LVD module (set the LVDEN bit in  
the LVDCON register).  
4. Wait for the LVD module to stabilize (the IRVST  
bit to become set).  
5. Clear the LVD interrupt flag, which may have  
falsely become set, until the LVD module has  
stabilized (clear the LVDIF bit).  
6. Enable the LVD interrupt (set the LVDIE and the  
GIE bits).  
Figure 22-4 shows typical waveforms that the LVD  
module may be used to detect.  
FIGURE 22-4:  
LOW VOLTAGE DETECT WAVEFORMS  
CASE 1:  
LVDIF may not be set  
VDD  
VLVD  
LVDIF  
Enable LVD  
Internally Generated  
Reference Stable  
TIVRST  
LVDIF cleared in software  
CASE 2:  
VDD  
VLVD  
LVDIF  
Enable LVD  
TIVRST  
Internally Generated  
Reference Stable  
LVDIF cleared in software  
LVDIF cleared in software,  
LVDIF remains set since LVD condition still exists  
DS39609A-page 236  
Advance Information  
2003 Microchip Technology Inc.