Maitiro ekudzivirira kutapurirana kwetambo mhedzisiro mune yekumhanyisa pcb dhizaini?

Maitiro ekudzivirira kutapurirana kwetambo mhedzisiro mu yakakwira-kumhanya pcb patani

1. Maitiro ekudzvanyirira kukanganiswa kwemagetsi emagetsi

Mhinduro yakanaka kuchinetso chekutendeka kwechiratidzo ichavandudza kusangana kwemagetsi (EMC) yebhodhi rePCB. Chimwe chezvinhu zvakakosha ndechekuona kuti bhodhi rePCB rine hwaro hwakanaka. Ratidziro yechiratidzo ine pasi pevhu inzira inoshanda kwazvo yekuumbika dhizaini. Uye zvakare, kudzikisa huwandu hwechiratidzo hwekunze kwekunze kwebhodhi redunhu zvakare inzira yakanaka yekudzikisa magetsi emagetsi. Iyi nzira inogona kuwanikwa nekushandisa “pamusoro nzvimbo” tekinoroji “kuvaka-kumusoro” pcb dhizaini. Iyo yepamusoro yenzvimbo nzvimbo inowanikwa kuburikidza nekuwedzera musanganiswa weakaonda kuputira zvidimbu uye ma micropores anoshandiswa kupinza matanda aya pane yakajairika-maitiro PCB. Kuramba uye kugona kugona kunogona kuvigwa pasi pechiso, uye kuenzana kwemitsara pauniti nzvimbo kunenge kwakapetwa kaviri, nokudaro kudzikisa huwandu hwePCB. Iko kuderedzwa kwenzvimbo yePCB ine simba rakakura pamusoro peiyo topology yekutenderera, zvinoreva kuti chiuno chazvino chaderedzwa, kureba kwekufambisa kwebazi kwadzikira, uye iro remagetsi remagetsi rinenge rakaenzana nenzvimbo yechino chiuno; At the same time, the small size characteristics mean that high-density pin packages can be used, which in turn reduces the length of the wire, thus reducing the current loop and improving emc characteristics.

2. Strictly control the cable lengths of key network cables

If the design has a high speed jump edge, the transmission line effect on the PCB must be considered. Iyo yakakwira wachi wachi inomhanya yakasanganiswa wedunhu machipisi anowanzo shandiswa nhasi akatonyanya kunetsa. Pane mamwe maitiro akakosha ekugadzirisa dambudziko iri: kana maseketi eCMOS kana TTL achishandiswa dhizaini, iyo frequency yekushandisa iri pasi pe10MHz, uye iyo wiring kureba haifanire kunge iri pamusoro pe7 inches. If the operating frequency is 50MHz, the cable length should not be greater than 1.5 inches. Wiring length should be 1 inch if operating frequency reaches or exceeds 75MHz. Iyo yakareba wiring kureba kweGaAs machipisi inofanira kunge iri 0.3 inches. Kana izvi zvapfuudzwa, pane dambudziko rekufambisa mutsara.

3. Ronga nemazvo topology yekukomberedza

Imwe nzira yekugadzirisa yekufambisa mutsara mhedzisiro ndeyekusarudza iyo chaiyo nzira yekufambisa uye yekupedzisira topology. Iyo cabling topology inoreva iko kuteedzana kwekabatidziro uye chimiro chetambo tambo. Kana madhivhaji ekumusoro-mhanya achishandiswa, chiratidzo chine mitsetse inokurumidza kuchinjika chinokanganiswa nematavi etrunk chiratidzo kunze kwekunge kureba kwebazi kuchichengetwa kupfupi. Kazhinji, pcb routing inotora maviri ekutanga topologies, anoti Daisy Chain nzira uye Star kugovera.

Kune daisy-cheni wiring, wiring inotangira pamagumo emutyairi uye inosvika kumagumo ega ega ekugamuchira. Kana akateedzana resistor achishandurwa kushandura chiratidzo chiratidzo, chinzvimbo cheiyo yakateedzana resistor chinofanira kunge chiri padyo nemagumo ekutyaira. Daisy cheni cabling ndiyo yakanakisa mukudzora kukwirisa kwepamusoro kwehomboni. Nekudaro, iyi mhando yewiring ine yakadzika kwazvo hutachiona chiyero uye hazvisi nyore kupasa 100%. Mukugadzirwa chaiko, isu tinoda kuita kuti kureba kwebazi muDaisy cheni wiring ipfupike sezvinobvira, uye iyo urefu hwakareba hunofanira kuve: Stub Delay < = Trt * 0.1.

Semuenzaniso, bazi rinopera neepamusoro-kumhanya TTL maseketi anofanirwa kunge ari pasi pe 1.5 inches pakureba. Iyi topology inotora isina wiring nzvimbo uye inogona kumisikidzwa neyechete resistor inoenderana. Nekudaro, iyi wiring chimiro inoita kuti chiratidzo chinogashira pane akasiyana chiratidzo chinogamuchira hachienderane.

The star topology can effectively avoid the problem of clock signal synchronization, but it is very difficult to finish the wiring manually on the PCB with high density. Kushandisa otomatiki cabler ndiyo nzira yakanakisa yekupedzisa nyeredzi kubaya. A terminal resistor is required on each branch. The value of the terminal resistance should match the characteristic impedance of the wire. Izvi zvinogona kuitwa nemaoko kana kuburikidza neCAD maturusi kuti uverenge hunhu impedance tsika uye terminal inowirirana kuramba maitiro.

While simple terminal resistors are used in the two examples above, a more complex matching terminal is optional in practice. Chekutanga sarudzo ndeye RC mechi terminal. RC dzinoenderana zviteshi zvinogona kudzora kushandiswa kwesimba, asi zvinogona chete kushandiswa kana chiratidzo chekushanda chisinga gadzikane. Iyi nzira inonyanya kukodzera wachi wachi chiratidzo chinowirirana kugadzirisa. Izvo zvinokanganisa ndezvekuti iyo capacitance muRC inoenderana terminal inogona kukanganisa chimiro uye kukurumidza kumhanya kwechiratidzo.

The series resistor matching terminal incurs no additional power consumption, but slows down signal transmission. This approach is used in bus-driven circuits where time delays are not significant. Iwo akateedzana resistor enzanisa chinongedzo zvakare ane mukana wekudzora huwandu hwemidziyo inoshandiswa pabhodhi uye kuwanda kwekubatana.

The final method is to separate the matching terminal, in which the matching element needs to be placed near the receiving end. Kubatsira kwayo ndeyekuti haizodonhedze chiratidzo, uye inogona kuve yakanaka kwazvo kudzivirira ruzha. Inowanzo shandiswa TTL yekuisa chiratidzo (ACT, HCT, FAST).

In addition, the package type and installation type of the terminal matching resistor must be considered. SMD surface mount resistors generally have lower inductance than through-hole components, so SMD package components are preferred. There are also two installation modes for ordinary straight plug resistors: vertical and horizontal.

Mune yakatwasuka yekumhanyisa maitiro, iko kushomeka kune ipfupi yekuisa pini, iyo inoderedza kupisa kwekushisa pakati pekupokana uye wedunhu bhodhi uye kunoita kuti kupisa kwekudzivirira kuve nyore kuburitswa mumhepo. Asi iyo yakatwasuka yakatwasuka yekumisikidza ichawedzera iyo inductance yeanopikisa. Horizontal kuisirwa ine yakaderera inductance nekuda yakaderera kuiswa. However, the overheated resistance will drift, and in the worst case, the resistance will become open, resulting in PCB wiring termination matching failure, becoming a potential failure factor.

4. Humwe hutekinoroji hunoshanda

Kuti uderedze inononoka magetsi kuwandisa pane IC magetsi, decoupling capacitor inofanirwa kuwedzerwa kuIC chip. Izvi zvinobudirira zvinobvisa kukanganisa kwemabhureki pane magetsi uye kunodzora mwaranzi kubva pachiuno chemagetsi pane rakadhindwa bhodhi.

Iyo burr inotsvedzerera mhedzisiro iri nani kana iyo decoupling capacitor yakabatana yakanangana kune yemagetsi magetsi gumbo redunhu rakabatanidzwa kwete kune iro gadziriro yemagetsi. Ichi chikonzero nei mamwe madhivha aine decoupling ma capacitor mumasokisi awo, nepo mamwe achida daro pakati peiyo decoupling capacitor uye chishandiso kuve chidiki zvakakwana.

Chero ipi yekumhanyisa mhanyisa uye yakakwira simba rekushandisa zvishandiso inofanirwa kuiswa pamwe pese pazvinokwanisika kudzikisira kwenguva inopfuura pamusoro pesimba remagetsi emagetsi.

Pasina tambo yemagetsi, tambo refu dzemagetsi dzinogadzira loop pakati pechiratidzo uye chiuno, chinoshanda senzvimbo yemwaranzi uye denderedzwa rinodzora.

Cabling inogadzira chiuno chisingapfuure kuburikidza neiyo imwechete tambo tambo kana imwe cabling inonzi yakavhurika chiuno. Kana chiuno chikapfuura nepakati chechetere netambo, dzimwe nzira dzinogadzira loop yakavharwa. Muzviitiko zvese izvi, iyo antenna athari (mutsara kanyanga uye mhete kanyanga) inogona kuitika.