IC697PCM711燃機(jī)通用卡件
將器件拆下并放置在紫外線燈下。任何液體滲透都會在染料發(fā)出的熒光下無所遁形。為提高開關(guān)電源產(chǎn)品的可靠性，開關(guān)電源會設(shè)計輸出過壓保護(hù)功能，防止產(chǎn)品內(nèi)部的某個元器件損壞后，導(dǎo)致輸出電壓升高。而電源后端的負(fù)載只能承受一定的電壓大小，一旦輸出電壓升高，會損壞電源后端的負(fù)載。為防止此問題發(fā)生，開關(guān)電源都會設(shè)計輸出過壓保護(hù)電路，從而提升系統(tǒng)可靠性工作。在電路中，一旦下拉電阻R2短路，根據(jù)計算公式知，Vo電壓會變?yōu)闊o窮大，一旦輸出電壓升高到一定值后，則會損壞電源的負(fù)載，導(dǎo)致系統(tǒng)燒壞。
IC697PCM711燃機(jī)通用卡件為防止此問題發(fā)生，在電路中增加輸出過壓保護(hù)電路。如圖2所示是輸出過壓保護(hù)電路的原理簡圖之一，其工作原理如下：一旦下拉電阻R2短路，輸出電壓往上升高，一旦輸出電壓升高到穩(wěn)壓二極管ZD1的擊穿電壓后，穩(wěn)壓二極管工作，把輸出電壓鉗位在穩(wěn)壓二極管的擊穿電壓值，防止輸出電壓繼續(xù)上升到無窮大，此時輸出電壓值被穩(wěn)壓二極管鉗位在擊穿電壓值大小，不會再上升。穩(wěn)壓二極管ZD1的規(guī)格參數(shù)值選型一般選取大于輸出電壓值2-3V即可。過壓保護(hù)電路適用于輸出功率小于75W以下的小功率電源產(chǎn)品中，對于大功率電源產(chǎn)品，輸出過壓保護(hù)電路的設(shè)計是控制原邊IC的工作，實(shí)現(xiàn)輸出過壓保護(hù)。當(dāng)產(chǎn)品過壓保護(hù)時，輸出電壓呈現(xiàn)打嗝輸出模式或是直接關(guān)斷輸出電壓，防止輸出功率過高損壞后級負(fù)載系統(tǒng)。由于電路比較復(fù)雜，在此不做原理說明。開關(guān)電源的輸出過壓保護(hù)電路的工作原理和作用。部分客戶在使用開關(guān)電源時，負(fù)載端存在輸出電壓倒灌現(xiàn)象，損壞開關(guān)電源產(chǎn)品或是導(dǎo)致開關(guān)電源產(chǎn)品無法正常工作。開關(guān)電源的過壓保護(hù)功能和電源防倒灌電壓功能是兩種不同的情況，不能混為一談。開關(guān)電源的過壓保護(hù)功能是電源向外的保護(hù)功能，防止外部負(fù)載系統(tǒng)損壞；而開關(guān)電源的防倒灌能力是指外部電壓對開關(guān)電源的影響力，避免產(chǎn)品的輸出端存在倒灌電壓時損壞開關(guān)電源，在此需要特別區(qū)分這兩種情況。在開關(guān)電源中，根據(jù)倒灌電壓產(chǎn)生的機(jī)理，輸出端存在反灌電壓的原因有如下幾種情況：
1、系統(tǒng)在不同的輸出電壓之間切換時會存在高壓電壓倒灌到低壓電源中，此問題在直流充電樁設(shè)備中比較常見；
2、開關(guān)電源的負(fù)載是感性負(fù)載，負(fù)載工作時會產(chǎn)生感應(yīng)電動勢，感應(yīng)電動勢生成的電壓倒灌到開關(guān)電源的輸出端；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
