IC697PCM711燃机通用卡件
将器件拆下并放置在紫外线灯下。任何液体渗透都会在染料发出的荧光下无所遁形。为提高开关电源产品的可靠性，开关电源会设计输出过压保护功能，防止产品内部的某个元器件损坏后，导致输出电压升高。而电源后端的负载只能承受一定的电压大小，一旦输出电压升高，会损坏电源后端的负载。为防止此问题发生，开关电源都会设计输出过压保护电路，从而提升系统可靠性工作。在电路中，一旦下拉电阻R2短路，根据计算公式知，Vo电压会变为无穷大，一旦输出电压升高到一定值后，则会损坏电源的负载，导致系统烧坏。
IC697PCM711燃机通用卡件为防止此问题发生，在电路中增加输出过压保护电路。如图2所示是输出过压保护电路的原理简图之一，其工作原理如下：一旦下拉电阻R2短路，输出电压往上升高，一旦输出电压升高到稳压二极管ZD1的击穿电压后，稳压二极管工作，把输出电压钳位在稳压二极管的击穿电压值，防止输出电压继续上升到无穷大，此时输出电压值被稳压二极管钳位在击穿电压值大小，不会再上升。稳压二极管ZD1的规格参数值选型一般选取大于输出电压值2-3V即可。过压保护电路适用于输出功率小于75W以下的小功率电源产品中，对于大功率电源产品，输出过压保护电路的设计是控制原边IC的工作，实现输出过压保护。当产品过压保护时，输出电压呈现打嗝输出模式或是直接关断输出电压，防止输出功率过高损坏后级负载系统。由于电路比较复杂，在此不做原理说明。开关电源的输出过压保护电路的工作原理和作用。部分客户在使用开关电源时，负载端存在输出电压倒灌现象，损坏开关电源产品或是导致开关电源产品无法正常工作。开关电源的过压保护功能和电源防倒灌电压功能是两种不同的情况，不能混为一谈。开关电源的过压保护功能是电源向外的保护功能，防止外部负载系统损坏；而开关电源的防倒灌能力是指外部电压对开关电源的影响力，避免产品的输出端存在倒灌电压时损坏开关电源，在此需要特别区分这两种情况。在开关电源中，根据倒灌电压产生的机理，输出端存在反灌电压的原因有如下几种情况：
1、系统在不同的输出电压之间切换时会存在高压电压倒灌到低压电源中，此问题在直流充电桩设备中比较常见；
2、开关电源的负载是感性负载，负载工作时会产生感应电动势，感应电动势生成的电压倒灌到开关电源的输出端；Sensors and transmitters such as motor current, water pump shaft temperature, motor temperature, drainage pipe flow, etc. are mainly used to monitor the operating conditions of water pumps and motors, and alarm when the limit is exceeded, so as to avoid damage to water pumps and motors. The digital input module of PLC collects various switching signals into PLC as the condition and basis of logic processing to control the start and stop of drainage pump. In the process of data acquisition, the processing of analog signal is to convert analog signal into digital signal (a/d conversion), and its conversion speed is determined by the sampling law. Generally, the sampling frequency should be more than 2 times of the highest frequency component in the analog signal, so that the accuracy of the a/d transformation can be completely restored to the original analog signal accuracy. The accuracy of a/d conversion depends on the number of bits of the a/d converter. For example, when the 5V voltage is required to be converted with the accuracy of 5mv, the accuracy is 5mv/5v=0.1%, that is, when the 1/1000 decimal 1000 is expressed in binary, it is required to be 10 bits, while the resolution of the a/d module used in this system is 16bit, and its accuracy is more than ± 0.05%, which
