對于連接(jie)到PC上的手機。由(you)于PC上電源輸出通常有很(hen)大的電(dian)感作為濾(lv)波器。當(dang)外部熱插(cha)拔(ba)或者系(xi)統(tong)開(kai)關機或其(qi)他(ta)的內部電(dian)源供(gong)電(dian)波動，都會(hui)使輸出電(dian)流發生快速(su)變化。最終(zhong)體現在(zai)USB端口，就會(hui)有一個(ge)尖峰(feng)電(dian)壓(ya)脈沖(chong)，而這個(ge)尖峰(feng)脈沖(chong)的幅度或者寬度有時會(hui)超出手(shou)機充(chong)電(dian)IC能承受的范圍(wei)，導致電(dian)源芯片的意外損壞(huai)。

對于一些第三方廠家提供的(de)(de)低成(cheng)本的(de)(de)USB充電(dian)(dian)器，由于設計時(shi)并未考慮良好的(de)(de)瞬態抑制(zhi)和調壓性能(neng)，所(suo)以未采取電(dian)(dian)源保護措施的(de)(de)手機(ji)在連接到這些第三方的(de)(de)充電(dian)(dian)器時(shi)就有可(ke)能(neng)發(fa)生損壞。

隨著手機屏幕的增大和(he)導(dao)航(hang)軟件的普及，用手機來做(zuo)汽(qi)車(che)導(dao)航(hang)的情形會(hui)(hui)越(yue)(yue)來越(yue)(yue)多。這(zhe)時(shi)候就需要連接(jie)(jie)手機到車(che)載充電(dian)(dian)器(qi)上(shang)以提供持久(jiu)的續航(hang)。大家都知道，汽(qi)車(che)上(shang)的電(dian)(dian)源(yuan)總線(xian)上(shang)存(cun)在很嚴(yan)重的污染(ran)。首(shou)先電(dian)(dian)瓶(ping)的的電(dian)(dian)壓范圍是8V-16V，蓄電(dian)(dian)池的電(dian)(dian)流很大，而且負載隨時(shi)可能會(hui)(hui)斷(duan)開(kai)(通過熔絲或(huo)繼電(dian)(dian)器(qi))。這(zhe)樣總線(xian)上(shang)就會(hui)(hui)產生超(chao)過電(dian)(dian)源(yuan)電(dian)(dian)壓幾倍的沖擊電(dian)(dian)壓，蓄電(dian)(dian)池誤接(jie)(jie)和(he)蓄電(dian)(dian)池雙倍電(dian)(dian)壓跳躍激活(huo)(24V)操(cao)作這(zhe)樣大操(cao)作也會(hui)(hui)造成(cheng)充電(dian)(dian)器(qi)輸入(ru)電(dian)(dian)壓超(chao)出標稱值。