系統(tǒng)級(jí)ESD：一盎司的預(yù)防勝過(guò)一磅重的治療

　　這些天來(lái)，我有更多的客戶互動(dòng)像我最近做的。這似乎是一個(gè)有點(diǎn)瘋狂的工程師為我們的團(tuán)隊(duì)在Semtech公司解決了他的系統(tǒng)級(jí)ESD問(wèn)題的一些第十一小時(shí)的幫助。這個(gè)家伙被一些煩人的ESD尖峰伏擊了。不僅他的產(chǎn)品沒有遵守，但他甚至看到ESD誘導(dǎo)失敗的一些早期田間試驗(yàn)。更糟糕的是，他很快就沒時(shí)間解決這些問(wèn)題了。他的管理變得越來(lái)越不耐煩，并增加壓力，有一個(gè)大的，苛刻的最終客戶等待這個(gè)產(chǎn)品。該計(jì)劃不能容忍另一個(gè)延遲，情況越來(lái)越嚴(yán)重，當(dāng)他向我們伸出手來(lái)。

　　當(dāng)我們與工程師更多地了解這個(gè)問(wèn)題的挑戰(zhàn)和性質(zhì)時(shí)，很明顯，有一些簡(jiǎn)單的東西，如果應(yīng)用在設(shè)計(jì)周期的前端，可以幫助創(chuàng)建一個(gè)“軟著陸”解決問(wèn)題。

　　First off， our friend had not implemented protection clamps at any of the I/O interfaces of the product. At a minimum， it would have been wise to layout the PCB pads for TVS clamps as a “safety valve” move should he need protection. Even if he did not populate those pads with ESD clamp devices， at least he would have allowed for the option to later do so. However， what really made this product an EMC challenge was the high-speed performance silicon driving the I/O. While the latest （65 nm， 45 nm and 28 nm） high-speed communication ICs offer incredible speed and power saving performance， they also tend to be more susceptible to latch-up or damage from fast rise-time ESD transients. As it was， even a weaker/lower threshold ESD zap could send his board out of commission.