對于電源適配器輸出過壓(ya)保護電(dian)路與欠壓(ya)保護電(dian)路，想必除了專業人(ren)士(shi)，很(hen)多(duo)人(ren)都(dou)不太清楚，今天(tian)我(wo)們就來給大家介紹一下(xia)，希(xi)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(yu)不確(que)定(ding)因素或電(dian)(dian)源內部(bu)故(gu)障導致輸出(chu)電(dian)(dian)壓(ya)高(gao)(gao)于(yu)額定(ding)值，觸(chu)發過壓(ya)保(bao)護電(dian)(dian)路(lu)對其電(dian)(dian)壓(ya)鉗(qian)位(wei)在設定(ding)值，從而達(da)到穩定(ding)輸出(chu)電(dian)(dian)壓(ya)值，比(bi)如一個12v2a的(de)電(dian)(dian)源適配器，在某故(gu)障影響下導致輸出(chu)電(dian)(dian)壓(ya)高(gao)(gao)于(yu)12V，過壓(ya)保(bao)護電(dian)(dian)路(lu)會把(ba)電(dian)(dian)壓(ya)鉗(qian)位(wei)在額定(ding)值12V。

　　輸出過壓(ya)時(shi)，加在VD3上的(de)電壓(ya)大于(yu)其(qi)穩壓(ya)值時(shi)，VD3導通，輸出電壓(ya)被鉗位，同(tong)時(shi)通過IC4向原邊反饋。

　　優點：

　　電路(lu)設計簡(jian)單 成本(ben)低(di)

　　缺點：

　　穩壓(ya)管VD3有(you)偏差會(hui)導致壓(ya)鉗位點上下浮動

　　應用(yong)的(de)注意事項(xiang)：

　　VD3應該選溫度系數較好(hao)的(de)穩(wen)壓管，需調(diao)試的(de)元件如R32應考(kao)慮多個并聯(lian)以方便調(diao)試。

　　當(dang)過壓保護電(dian)路(lu)起(qi)作用時，電(dian)路(lu)處(chu)于非(fei)正常工(gong)作狀態。對于有輸(shu)(shu)出電(dian)壓上(shang)下調功能的電(dian)路(lu)，過壓保護點應大于輸(shu)(shu)出電(dian)壓上(shang)調最(zui)大值

　　2、輸出過壓保護電路二：

　　輸(shu)出過(guo)壓保護電(dian)(dian)路：與過(guo)壓保護電(dian)(dian)路一一樣，在(zai)輸(shu)出電(dian)(dian)壓高(gao)于額(e)定值(zhi)，觸發(fa)保護電(dian)(dian)路，不(bu)過(guo)其電(dian)(dian)路結構(gou)不(bu)一樣。

　　輸出過壓(ya)時，Va>Vref，IC3導通，通過IC4向原邊反饋,輸出電壓(ya)穩定在設定的過壓(ya)保(bao)護值。

　　優點(dian)：輸出(chu)過壓保護值(zhi)可以(yi)精確(que)設(she)置。

　　缺點(dian)：相對(dui)穩(wen)壓管鉗(qian)位方式成本(ben)稍高一(yi)些。

　　應用的注意事項(xiang)：

　　當過(guo)壓保(bao)護電(dian)路(lu)起作用時，電(dian)路(lu)處于(yu)(yu)非(fei)正常工作狀態。對于(yu)(yu)有輸出電(dian)壓上(shang)下調(diao)功(gong)能的電(dian)路(lu)，過(guo)壓保(bao)護點應大(da)(da)于(yu)(yu)輸出電(dian)壓上(shang)調(diao)最(zui)大(da)(da)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)類電源適配器輸入(ru)欠(qian)壓(ya)電路：保(bao)護原理(li)為電壓(ya)輸入(ru)低(di)(di)于額(e)定(ding)值(zhi)時或低(di)(di)于保(bao)護電壓(ya)值(zhi)時會拉低(di)(di)控(kong)制芯片的(de)(de)供電VCC達到關閉輸出的(de)(de)目的(de)(de)。

　　其實現原理為：

　　當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源輸入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)高(gao)(gao)(gao)于(yu)(yu)欠壓(ya)(ya)保護(hu)設(she)定點(dian)時， A 點(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)高(gao)(gao)(gao)于(yu)(yu) U4 的 Vref , U4 導(dao)通(tong)， B 點(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)為(wei)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平， 04 導(dao)通(tong)， Vcc 供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)正(zheng)常：當(dang)輸入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)低(di)于(yu)(yu)保護(hu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)時， A 點(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)低(di)于(yu)(yu) U4 的 Vref , U4 截止(zhi)， B 點(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)為(wei)高(gao)(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平， Q4 截止(zhi)，導(dao)致 Vcc 沒(mei)有(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，這時 Vre 他(ta)為(wei)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平，A點(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)隨輸入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)增高(gao)(gao)(gao)而增高(gao)(gao)(gao)，高(gao)(gao)(gao)于(yu)(yu)U4 的 Vref時模塊(kuai)變為(wei)正(zheng)常工作，R4 可以設(she)定欠壓(ya)(ya)保護(hu)點(dian)的回(hui)差。

　　優點：電路結構簡單，保(bao)護點精準

　　缺(que)點：費用成本太高

　　應用的(de)注意(yi)事項：使用時注意(yi) R , , RZ 的(de)取值，有時候需要(yao)兩個(ge)電阻并聯(lian)才能得(de)到(dao)需要(yao)的(de)保護點。還需要(yao)注意(yi) R1 , RZ 的(de)溫度系數(shu)，否則高低溫時，欠(qian)壓(ya)保護點相差較(jiao)大。

　　2、輸入欠壓保護電路二：

　　二(er)類欠(qian)壓保(bao)護電路：輸(shu)入(ru)電壓高于欠(qian)壓值正常(chang)接通，低(di)于欠(qian)壓值自動關(guan)閉輸(shu)出。

　　其實現原理為：

　　輸(shu)入電壓(ya)(ya)在正常工(gong)作范圍內(nei)時(shi)(shi)， Va大于(yu)(yu)VD4的穩(wen)壓(ya)(ya)值，VT4導(dao)(dao)通(tong)(tong)(tong)，Vb為(wei)0電位，VT5截止， 此(ci)時(shi)(shi)保(bao)護電路不起(qi)作用;當輸(shu)入電壓(ya)(ya)低于(yu)(yu)設定欠壓(ya)(ya)值時(shi)(shi)，Va小于(yu)(yu)VD4的穩(wen)壓(ya)(ya)值，VT4截止，Vb為(wei)高(gao)電位，VT5導(dao)(dao)通(tong)(tong)(tong)，將COMP(芯片的1腳)拉到0電位，芯片關閉輸(shu)出，從而實現了欠壓(ya)(ya)保(bao)護功能。 R21、VT6、R23組成欠壓(ya)(ya)關斷、恢復(fu)時(shi)(shi)的回差電路。當欠壓(ya)(ya)關斷時(shi)(shi),VT6導(dao)(dao)通(tong)(tong)(tong)，將R21與R2并(bing)聯，

　　恢復時，VT6截止(zhi)

　　回差電壓即(ji)為(wei)(Vin’-Vin)

　　優點：電路形式(shi)簡單，成本較低(di)。

　　缺點(dian)：每(mei)一個穩壓管VD4的(de)穩壓值(zhi)(zhi)都有誤差(cha)，導致欠壓保護(hu)值(zhi)(zhi)隨之波動(dong)，當大(da)批量生產的(de)時候需要調試相關值(zhi)(zhi)

　　應用的注意事項：VD4應該(gai)選溫度系數較好的穩壓管，需調(diao)試的元件(jian)如R2應考(kao)慮(lv)多(duo)個(ge)并(bing)聯以方便(bian)調(diao)試。

　　對(dui)于電源(yuan)適配器輸(shu)出(chu)過壓(ya)保(bao)護(hu)電路(lu)與欠(qian)壓(ya)保(bao)護(hu)電路(lu)就介紹到這里，如(ru)果(guo)您(nin)還有(you)什么疑問可以聯(lian)系(xi)我們，我們會為(wei)您(nin)詳細解答!