led電路的比較

　　近年來(lái)，發(fā)光二極管（LED）已成為傳統(tǒng)光源的一種可行的替代品。長(zhǎng)壽命、高效率、體積小、反應(yīng)時(shí)間短的優(yōu)點(diǎn)使白熾燈泡的數(shù)量不斷增加。一個(gè)市場(chǎng)，這種變化已經(jīng)成為最明顯的是汽車，在使用LED背光儀表盤和開關(guān)不僅，而且在中央高位剎車燈（CHMSL）外部照明，后組合燈（RCL），轉(zhuǎn)向信號(hào)燈和水坑照明。

　　盡管壽命長(zhǎng)的LED故障率低，汽車可以發(fā)現(xiàn)，有時(shí)，在他們失敗的LED高位剎車燈。這通常是由于有缺陷的電路設(shè)計(jì)，其中LED燈是可以過(guò)?？紤]到這個(gè)假設(shè)，編寫了這個(gè)應(yīng)用說(shuō)明：識(shí)別、描述和評(píng)論串行和矩陣電路中的LED行為和故障模式。

　　Failure modes of LEDs

　　Ultimately there are two possible failure modes for LEDs： light degradation and total failure. Light degradation occurs when the emitted light falls to 50 percent of its’ initial value. This is due simply to aging of the LED. The second failure mode， total failure， is caused by an open contact between the Chip and the lead frame， between the Chip and the bond wire or between the bond wire and the lead frame. The reason for this failure is an overheating of the LED past the glass point of the resin. This leads to a softening of the resin， and when the resin material cools and becomes hard once again， mechanical forces on the bond wire cause an open contact.