對于電源適配器輸(shu)出過壓保護電路(lu)與(yu)欠壓保護電路(lu)，想(xiang)必除(chu)了專業人(ren)士，很多人(ren)都(dou)不(bu)太清楚，今天我(wo)們就(jiu)來(lai)給大家介(jie)紹(shao)一下，希望可以幫到大家!

　　一、電源適配器輸出過壓保護電路

　　1、輸出過壓保護電路一：

　　由于不確定(ding)因素(su)或電(dian)(dian)(dian)源內部故障導(dao)致(zhi)輸(shu)(shu)出電(dian)(dian)(dian)壓(ya)高于額定(ding)值(zhi)，觸發(fa)過(guo)(guo)壓(ya)保(bao)護電(dian)(dian)(dian)路(lu)對其電(dian)(dian)(dian)壓(ya)鉗(qian)位(wei)在(zai)設定(ding)值(zhi)，從而達(da)到穩(wen)定(ding)輸(shu)(shu)出電(dian)(dian)(dian)壓(ya)值(zhi)，比如一個12v2a的(de)電(dian)(dian)(dian)源適配器(qi)，在(zai)某故障影響下導(dao)致(zhi)輸(shu)(shu)出電(dian)(dian)(dian)壓(ya)高于12V，過(guo)(guo)壓(ya)保(bao)護電(dian)(dian)(dian)路(lu)會把電(dian)(dian)(dian)壓(ya)鉗(qian)位(wei)在(zai)額定(ding)值(zhi)12V。

　　輸出過(guo)壓(ya)(ya)時，加(jia)在VD3上(shang)的電(dian)壓(ya)(ya)大于其(qi)穩(wen)壓(ya)(ya)值時，VD3導(dao)通，輸出電(dian)壓(ya)(ya)被鉗位，同時通過(guo)IC4向原(yuan)邊(bian)反饋。

　　優點：

　　電(dian)路設計簡單 成本低

　　缺點：

　　穩壓(ya)(ya)管(guan)VD3有偏(pian)差會導致(zhi)壓(ya)(ya)鉗位點上下浮動

　　應(ying)用的注意事項(xiang)：

　　VD3應該選溫度系數較(jiao)好的(de)穩壓管，需調試的(de)元件如(ru)R32應考慮多個并聯以方(fang)便調試。

　　當過(guo)壓(ya)保護電路起作用(yong)時，電路處(chu)于(yu)非(fei)正常工作狀態。對于(yu)有(you)輸出(chu)電壓(ya)上下調功能(neng)的(de)電路，過(guo)壓(ya)保護點應大于(yu)輸出(chu)電壓(ya)上調最大值

　　2、輸出過壓保護電路二：

　　輸出過壓(ya)(ya)(ya)保(bao)護(hu)電(dian)(dian)路(lu)：與過壓(ya)(ya)(ya)保(bao)護(hu)電(dian)(dian)路(lu)一一樣，在(zai)輸出電(dian)(dian)壓(ya)(ya)(ya)高于額定值，觸發保(bao)護(hu)電(dian)(dian)路(lu)，不過其電(dian)(dian)路(lu)結構不一樣。

　　輸出過壓時，Va>Vref，IC3導通，通過IC4向(xiang)原邊反饋,輸出電(dian)壓穩定在設(she)定的過壓保護值(zhi)。

　　優點：輸出過壓保護(hu)值可以精確設置(zhi)。

　　缺點(dian)：相對穩壓管鉗位(wei)方式成本稍高一些(xie)。

　　應用的(de)注(zhu)意事項：

　　當(dang)過壓(ya)保(bao)護(hu)電(dian)(dian)路(lu)起作(zuo)用時，電(dian)(dian)路(lu)處于非正常(chang)工作(zuo)狀態。對于有輸(shu)出電(dian)(dian)壓(ya)上下調功能的(de)電(dian)(dian)路(lu)，過壓(ya)保(bao)護(hu)點(dian)應大于輸(shu)出電(dian)(dian)壓(ya)上調最大值。

　　二、電源適配器的欠壓保護電路

　　1、輸入欠壓保護電路一：

　　一(yi)類電(dian)(dian)(dian)源適配器輸入欠(qian)壓電(dian)(dian)(dian)路(lu)：保(bao)護(hu)原理為電(dian)(dian)(dian)壓輸入低(di)于(yu)額定值(zhi)時(shi)或低(di)于(yu)保(bao)護(hu)電(dian)(dian)(dian)壓值(zhi)時(shi)會拉低(di)控制芯片的(de)供電(dian)(dian)(dian)VCC達到(dao)關(guan)閉(bi)輸出的(de)目的(de)。

　　其實現原理為：

　　當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源輸入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)高(gao)于(yu)欠(qian)(qian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)保護設(she)定點(dian)(dian)(dian)時， A 點(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)高(gao)于(yu) U4 的 Vref , U4 導(dao)通， B 點(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)為(wei)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)， 04 導(dao)通， Vcc 供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)正常：當輸入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)低(di)于(yu)保護電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)時， A 點(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)低(di)于(yu) U4 的 Vref , U4 截止， B 點(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)為(wei)高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)， Q4 截止，導(dao)致 Vcc 沒有電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)，這時 Vre 他(ta)為(wei)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，A點(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)隨輸入電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)增高(gao)而增高(gao)，高(gao)于(yu)U4 的 Vref時模(mo)塊(kuai)變為(wei)正常工作，R4 可以設(she)定欠(qian)(qian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)保護點(dian)(dian)(dian)的回差。

　　優(you)點：電路結構簡(jian)單，保護點精準

　　缺點：費用成(cheng)本(ben)太高

　　應用(yong)的(de)注意事項：使用(yong)時注意 R , , RZ 的(de)取值，有(you)時候需(xu)要(yao)兩個(ge)電阻并(bing)聯才能(neng)得到需(xu)要(yao)的(de)保護點(dian)。還(huan)需(xu)要(yao)注意 R1 , RZ 的(de)溫度系數，否則(ze)高(gao)低溫時，欠壓保護點(dian)相差較大。

　　2、輸入欠壓保護電路二：

　　二類欠壓(ya)保(bao)護(hu)電路：輸入電壓(ya)高于欠壓(ya)值(zhi)正常(chang)接通，低(di)于欠壓(ya)值(zhi)自動關閉輸出。

　　其實現原理為：

　　輸入(ru)電壓(ya)(ya)(ya)(ya)在正常工作(zuo)范圍內時(shi)， Va大于(yu)VD4的(de)穩壓(ya)(ya)(ya)(ya)值，VT4導通(tong)，Vb為0電位(wei)(wei)(wei)，VT5截(jie)止(zhi)， 此時(shi)保(bao)護電路不起作(zuo)用;當輸入(ru)電壓(ya)(ya)(ya)(ya)低于(yu)設定欠(qian)(qian)壓(ya)(ya)(ya)(ya)值時(shi)，Va小于(yu)VD4的(de)穩壓(ya)(ya)(ya)(ya)值，VT4截(jie)止(zhi)，Vb為高電位(wei)(wei)(wei)，VT5導通(tong)，將COMP(芯片的(de)1腳)拉(la)到0電位(wei)(wei)(wei)，芯片關閉輸出，從而實現了欠(qian)(qian)壓(ya)(ya)(ya)(ya)保(bao)護功能。 R21、VT6、R23組成欠(qian)(qian)壓(ya)(ya)(ya)(ya)關斷、恢復(fu)時(shi)的(de)回差電路。當欠(qian)(qian)壓(ya)(ya)(ya)(ya)關斷時(shi),VT6導通(tong)，將R21與R2并聯，

　　恢復(fu)時(shi)，VT6截止

　　回差電壓即為(Vin’-Vin)

　　優點：電路(lu)形式簡(jian)單，成本較低。

　　缺點：每一個穩壓管VD4的穩壓值都(dou)有誤差，導致(zhi)欠壓保護值隨之波動，當大批量(liang)生產的時候(hou)需(xu)要調(diao)試相(xiang)關值

　　應(ying)用的注意事項：VD4應(ying)該選溫度系數(shu)較好(hao)的穩壓管(guan)，需調試的元件如R2應(ying)考慮(lv)多個并聯以方便調試。

　　對于電(dian)源適配(pei)器輸(shu)出過(guo)壓保護電(dian)路(lu)與欠壓保護電(dian)路(lu)就介紹到(dao)這里，如(ru)果您還有什么(me)疑問可以(yi)聯系我(wo)們，我(wo)們會為(wei)您詳細解答!