为了确保正常工作,大多数基于微处理器的系统在上电和掉电过程中以及进入或退出关闭或睡眠方式时都要求监控.监控器可能仅提供上电复位,也可能提供其他功能,如后备电池管理,存贮器写保护,低电平早期告警或软件看门狗(图1).你可以通过选择微处理器监控器IC(也称上电复位、电源导通电路、复位电路等)一次或按不同组合得到这些功能.下述讨论将帮助你选择最适合你的应用型号,并为许多常见的μP监控器问题提供解决方案.首先,确定发生复位的V_(CC)门限电压.(当电源电压在容限范围之外时,复位的确定会阻碍μP工作.)典型上电复位电路由电压基准、比较器和定时器组成,通过比较其准电压和V_(CC)上升沿(通过 To ensure proper operation, most microprocessor-based systems require monitoring during power-up and power-down, as well as entering or exiting shutdown or sleep modes. The monitor may provide only a power-on reset and may also provide other features such as Backup battery management, memory write protection, low-level early warning or software watchdog (Figure 1) .You can select the microprocessor monitor IC (also known as power-on reset, power on circuit, reset circuit, etc. ) These functions are available at once or in different combinations.The following discussion will help you select the most appropriate application for your application and provide solutions to many common μP monitor problems.First, determine the V CC threshold at which a reset occurs. (When the supply voltage is outside the tolerance range, the determination of reset will hinder μP operation.) A typical power-on reset circuit consists of a voltage reference, a comparator, and a timer. By comparing its quasi-voltage with the rising edge of V CC by