In liwiro PCB kupanga, kugwiritsa ntchito chizindikiro chosiyana (DIFferential Signal) kukuchulukirachulukira, ndipo chizindikiro chovuta kwambiri muderali nthawi zambiri chimapangidwa ndi mawonekedwe osiyana. N’chifukwa chiyani zili choncho? Poyerekeza ndi njira wamba yokhala ndi malekezero amodzi, ma siginecha amasiyanitsa ali ndi zabwino zake zotsutsana ndi kusokoneza, kupondereza koyenera kwa EMI, komanso kuyika nthawi yake.

Zofunikira za waya za PCB zosiyana

Pa bolodi loyang’anira dera, mizere yosiyana iyenera kukhala mizere iwiri yofanana kutalika, yofanana m’lifupi, moyandikana, ndi pamlingo womwewo.

1. Utali wofanana: Utali wofanana umatanthauza kuti utali wa mizere iwiriyo uyenera kukhala wautali momwe kungathekere, kuti zitsimikizire kuti zizindikiro ziwiri zosiyanitsa zimasunga ma polar osiyanasiyana nthawi zonse. Kuchepetsa wamba mode zigawo zikuluzikulu.

2. M’lifupi mwake ndi mtunda wofanana: M’lifupi mwake m’lifupi mwake kumatanthauza kuti m’lifupi mwa zizindikiro za zizindikiro ziwirizo ziyenera kusungidwa mofanana, ndipo mtunda wofananawo umatanthauza kuti mtunda wa pakati pa mawayawo uyenera kukhala wokhazikika komanso wofanana.

3. Kusintha kwakung’ono kwa impedance: Popanga PCB yokhala ndi zizindikiro zosiyana, chimodzi mwazinthu zofunika kwambiri ndikupeza kulepheretsa kwa ntchitoyo, ndikukonzekera masiyanidwewo moyenerera. Kuphatikiza apo, sungani kusintha kwa impedance kukhala kochepa momwe mungathere. Kulepheretsa kwa mzere wosiyanitsa kumadalira zinthu monga kutsata m’lifupi, kuphatikizika, makulidwe amkuwa, ndi zinthu za PCB ndi stackup. Mukamayesetsa kupewa chilichonse chomwe chimasintha kusagwirizana kwa awiriwa, ganizirani aliyense wa iwo.

Kusamvetsetsana wamba pamapangidwe azizindikiro za PCB

Kusamvetsetsana 1: Zimakhulupirira kuti chizindikiro chosiyana sichifuna ndege yapansi ngati njira yobwerera, kapena kuti zizindikiro zosiyana zimapereka njira yobwerera kwa wina ndi mzake.

Chifukwa cha kusamvetsetsana kumeneku ndikuti amasokonezedwa ndi zochitika zapamwamba, kapena njira yotumizira zizindikiro zothamanga kwambiri sizozama mokwanira. Mabwalo osiyanasiyana sakhudzidwa ndi kugunda kwapansi kofananira ndi zizindikiro zina zaphokoso zomwe zitha kukhalapo pamagetsi ndi ndege zapansi. Kuchotsedwa kwapang’ono kwa ndege yapansi sikutanthauza kuti dera losiyana siligwiritsa ntchito ndege yowonetsera ngati njira yobwereranso chizindikiro. M’malo mwake, pakuwunika kobwereza kwa ma siginecha, makina amawaya osiyanitsa ndi mawaya wamba okhala ndi mawotchi amodzi ndi ofanana, ndiye kuti, ma siginecha apamwamba nthawi zonse amakhala Reflow motsatira lupu ndi inductance yaying’ono kwambiri. Kusiyanitsa kwakukulu ndikuti kuwonjezera pa kugwirizana pansi, mzere wosiyana umakhalanso ndi mgwirizano wogwirizana. Ndi mtundu uti wolumikizana womwe uli wamphamvu, ndi uti womwe umakhala njira yayikulu yobwerera.

M’mapangidwe a dera la PCB, kulumikizana pakati pa kusiyanasiyana kumakhala kochepa, nthawi zambiri kumangowerengera 10-20% ya digiri yolumikizira, ndipo zambiri ndikulumikizana pansi, kotero njira yayikulu yobwereranso yosiyana ikadalipo pansi. ndege . Pakakhala discontinuity mu ndege yapansi, kugwirizana pakati pa mayendedwe osiyana m’deralo popanda ndege zolozera kudzapereka njira yaikulu yobwerera, ngakhale kuti discontinuity ya ndege yolozera alibe mphamvu pa kusiyana kusiyana pa wamba wamba inatha. kutsata Ndizovuta, koma zidzachepetsabe mtundu wa chizindikiro chosiyana ndikuwonjezera EMI, zomwe ziyenera kupewedwa momwe zingathere.

Kuphatikiza apo, okonza ena amakhulupirira kuti ndege yolozera yomwe ili pansi pa njira yosiyana imatha kuchotsedwa kuti itseke gawo la chizindikiro chodziwika bwino pakupatsirana kosiyana. Komabe, njira iyi si yofunikira m’malingaliro. Momwe mungaletsere impedance? Kusapereka cholumikizira chapansi pa siginecha wamba kungayambitse ma radiation a EMI. Njira imeneyi imavulaza kwambiri kuposa zabwino.

Kusamvetsetsa 2: Amakhulupirira kuti kusungitsa mipata yofanana ndikofunikira kuposa kufananiza kutalika kwa mzere.

M’mapangidwe enieni a PCB, nthawi zambiri sizingatheke kukwaniritsa zofunikira zamapangidwe osiyanitsa nthawi imodzi. Chifukwa cha kukhalapo kwa zinthu monga kugawa kwa pini, vias, ndi danga la mawaya, cholinga cha kufananitsa kutalika kwa mzere chiyenera kutheka kupyolera mu mapindikidwe oyenera, koma zotsatira zake ziyenera kukhala kuti madera ena osiyanitsa awiriwo sangafanane. Lamulo lofunikira kwambiri pamapangidwe amitundu yosiyanasiyana ya PCB ndi kutalika kwa mzere wofananira. Malamulo ena amatha kugwiridwa mosinthasintha malinga ndi zofunikira za mapangidwe ndi ntchito zenizeni.

Kusamvetsetsa 3: Ganizirani kuti mawaya osiyanitsa ayenera kukhala oyandikana kwambiri.

Kusunga kusiyana kwapafupi sikuli kanthu kena koma kupititsa patsogolo kulumikizana kwawo, komwe sikungangowonjezera chitetezo chokwanira ku phokoso, komanso kugwiritsa ntchito mokwanira polarity yosiyana ndi maginito kuti athetse kusokoneza kwa ma elekitiroma kudziko lakunja. Ngakhale kuti njira imeneyi ndi yopindulitsa kwambiri nthawi zambiri, siili mtheradi. Ngati tingathe kuonetsetsa kuti ali otetezedwa mokwanira kuti asasokonezedwe ndi kunja, ndiye kuti sitiyenera kugwiritsa ntchito kugwirizanitsa mwamphamvu kuti tikwaniritse zotsutsana. Ndipo cholinga chopondereza EMI.

Kodi tingatsimikizire bwanji kudzipatula kwabwino ndi kutetezedwa kwa mitundu yosiyanasiyana? Kuchulukitsa katalikirana ndi zizindikiro zina ndi imodzi mwa njira zofunika kwambiri. Mphamvu yamagetsi yamagetsi imachepa ndi masikweya amtunda. Nthawi zambiri, mizere ikadutsa kuwirikiza kanayi kukula kwa mzere, kusokoneza kumakhala kofooka kwambiri. Zitha kunyalanyazidwa.