DS200SDCIG1A為抑制電源和地線噪聲,筆者認(rèn)為在車用VCD設(shè)計(jì)中可采取以下措施:(1)、選用貼片元件和盡可能縮短元件的引腳長度,以減小元件分布電感的影響;選用噪聲容限大的數(shù)字IC。(2)、在VDD及VOC電源端盡可能靠近器件接入濾波電容,以縮短開關(guān)電流的流通途徑,DS200SDCIG1A用10μF鋁電解和0.1μF獨(dú)石電容并聯(lián)接在電源腳上。對(duì)于MPEG板主電源輸入端和MPEG解碼芯片以及DRAM,SDRAM等高速數(shù)字IC的電源端可用鉭電解電容代替鋁電解電容,因?yàn)楦哳l時(shí)鉭電解的對(duì)地阻抗比鋁電解小得多。(3)、印制板布局時(shí),要將模擬電路區(qū)和數(shù)字電路區(qū)合理地分開,電源和地線單獨(dú)引出,電源供給處匯集到一點(diǎn);PCB布線時(shí),高頻數(shù)字信號(hào)線要用短線,主要信號(hào)線最好集中在PCB板中心,時(shí)鐘發(fā)生電路應(yīng)在板中心附近,時(shí)鐘扇出應(yīng)采用菊鏈?zhǔn)交虿⒙?lián)布線,電源線盡可能遠(yuǎn)離高頻數(shù)字信號(hào)線或用地線隔開。(4)、印制板的電源線和地線印制條盡可能寬,以減小線電阻,從而減小公共阻抗引起的干擾噪聲。(5)、對(duì)數(shù)模混合電路,VDD與VOC應(yīng)連到模擬電源VOC,AGND與DGND接到模擬地AGND。根據(jù)BB,PHILIPS,ALPINE公司實(shí)驗(yàn)結(jié)果,建議把D/A器件視為模擬器件,MPEG電路與D/A器件連接中,D/A器件必須置于AGND上,同時(shí)要提供一條數(shù)字回路供這些數(shù)字噪聲/能量反饋回信號(hào)源,以減小數(shù)字器件的噪聲對(duì)模擬電路的影響
DS200SDCIG1A
DS200SDCCG5A
DS200SDCCG4A
DS200SDCCG3A
DS200SDCCG2A
DS200SSBAG1B
DS200SSBAG1A
DS200SPCBG1A
DS200SNPAH1A
DS200SLCCG4A
DS200SLCCG3A
DS200SLCCG2A
DS200SLCCG1A
DS200SLCCG1A
DS200SIOCG1A
DS200SIOBH1A
DS200TBCBG1A
DS200TBCAG2A
DS200TBCAG1A
DS200SVMAG1A
DS200SVIAG1A
DS200STCAG1A
DS200STBAG1A
DS200SSRAG1A
DS200SSBBG1A
DS200TCCAG1B
DS200TCCAG1A
DS200TBQGG1A
DS200TBQEG1B
DS200TBQDG1A
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