Yadda za a guji tasirin layin watsawa a ciki PCB mai sauri zane

1. Hanyoyin danne tsangwama na electromagnetic

Kyakkyawan mafita ga matsalar mutuncin siginar zai inganta karfin wutar lantarki (EMC) na hukumar PCB. Daya daga cikin mafi mahimmanci shine tabbatar da cewa hukumar PCB tana da kyakkyawan tushe. Layer siginar tare da ƙasa ƙasa hanya ce mai inganci don ƙira mai rikitarwa. Bugu da ƙari, rage girman siginar siginar da ke saman saman allon kewaye ita ma hanya ce mai kyau don rage hasken wutar lantarki. Ana iya samun wannan hanyar ta amfani da fasahar “farfajiya” fasahar “ginawa” ƙirar PCB. Ana samun faɗin yankin saman ta ƙara haɗe da yadudduka ruɓaɓɓen rufi da micropores da ake amfani da su don ratsa waɗannan yadudduka akan PCB na gaba-gaba. Za a iya binne juriya da ƙarfin a ƙarƙashin farfajiya, kuma girman layin kowane yanki yana kusan ninki biyu, don haka rage ƙimar PCB. Rage yankin PCB yana da babban tasiri kan yanayin topology, wanda ke nufin cewa an rage madauki na yanzu, an rage tsawon layin reshe, kuma hasken lantarki yana da kusan daidai da yankin madauki na yanzu; 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. Babban agogo mai saurin haɗa kwakwalwan da’irar da aka saba amfani da su a yau sun fi matsala. Akwai wasu ƙa’idodi na asali don warware wannan matsalar: idan ana amfani da da’irar CMOS ko TTL don ƙira, mitar aiki bai wuce 10MHz ba, kuma tsayin wayoyin bai kamata ya fi inci 7 ba. 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. Matsakaicin tsawon wayoyi don kwakwalwan kwamfuta na GaAs ya zama inci 0.3. Idan an wuce wannan, akwai matsalar layin watsawa.

3. Daidaita tsarin topology na cabling

Wata hanya don warware tasirin layin watsawa shine zaɓi madaidaicin hanyar juyawa da topology na ƙarshe. Topology na cabling yana nufin jerin cabling da tsarin kebul na cibiyar sadarwa. Lokacin da ake amfani da na’urorin dabaru masu saurin gudu, siginar tare da gefuna masu saurin canzawa za ta gurbata ta rassan akwatunan siginar sai dai idan an rage tsawon reshen sosai. Gabaɗaya, zirga -zirgar PCB tana ɗaukar topologies na asali guda biyu, wato Daisy Chain routing da rarraba Star.

Don wayoyin sarkar daisy, wayoyi yana farawa daga ƙarshen direba kuma ya kai kowane ƙarshen karɓar bi da bi. Idan ana amfani da jerin tsayayyun jeri don canza halayen siginar, matsayin juriya na jerin yakamata ya kasance kusa da ƙarshen tuƙi. Haɗin sarkar Daisy shine mafi kyau don sarrafa babban tsangwama na jituwa. Koyaya, wannan nau’in wiring yana da mafi ƙarancin ƙimar watsawa kuma ba mai sauƙin wucewa 100%ba. A cikin ainihin ƙirar, muna son yin tsawon reshe a cikin wayoyin sarkar Daisy a takaice kamar yadda zai yiwu, kuma ƙimar tsayin amintaccen yakamata ya kasance: Jinkirin jinkiri < = Trt * 0.1.

Misali, reshe ya ƙare a cikin manyan hanyoyin TTL masu sauri yakamata ya zama ƙasa da inci 1.5. Wannan topology yana ɗaukar sarari mara waya sosai kuma ana iya ƙare shi ta hanyar daidaituwa guda ɗaya. Koyaya, wannan tsarin wayoyi yana sa siginar karɓa a mai karɓar siginar daban ba ta daidaita ba.

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. Amfani da kebul na atomatik shine hanya mafi kyau don kammala cabling star. A terminal resistor is required on each branch. The value of the terminal resistance should match the characteristic impedance of the wire. Ana iya yin wannan da hannu ko ta kayan aikin CAD don ƙididdige ƙimomin ɗabi’ar halayyar da ƙimar juriya.

While simple terminal resistors are used in the two examples above, a more complex matching terminal is optional in practice. Zaɓin farko shine tashar wasan RC. Tashoshin da suka dace da RC na iya rage yawan amfani da wuta, amma ana iya amfani da shi kawai lokacin da siginar ta yi ƙarfi. Wannan hanyar ita ce mafi dacewa da aikin daidaita siginar layin agogo. Rashin hasara shine ƙarfin da ke cikin madaidaicin tashar RC na iya shafar sifar da saurin siginar.

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. Jerin mai jituwa mai jituwa shima yana da fa’idar rage yawan na’urorin da ake amfani da su a kan jirgin da kuma yawan haɗin haɗi.

The final method is to separate the matching terminal, in which the matching element needs to be placed near the receiving end. Amfaninta shine cewa ba zai saukar da siginar ba, kuma yana iya zama da kyau don gujewa hayaniya. Yawanci ana amfani dashi don siginar shigar TTL (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.

A cikin yanayin hawa na tsaye, juriya yana da ɗan gajeren abin hawa, wanda ke rage juriya na zafi tsakanin juriya da allon kewaye kuma yana sa zafin juriya ya fi sauƙi a cikin iska. Amma tsawaitawa a tsaye zai ƙara haɓaka shigarwar. A kwance shigarwa yana da ƙananan inductance saboda ƙananan shigarwa. 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. Sauran fasahohin da suka dace

Don rage yawan wuce haddi na ƙarfin wutar lantarki akan wutar lantarki na IC, yakamata a ƙara ƙaramin capacitor zuwa guntu IC. Wannan yana cire tasirin burrs yadda yakamata akan wutar lantarki kuma yana rage radadi daga madafan ikon akan allon da aka buga.

Tasirin santsi na burr shine mafi kyau lokacin da aka haɗa madaidaicin ƙarfin wutar kai tsaye zuwa ƙafar wutar lantarki na haɗaɗɗiyar da’irar maimakon madaidaicin wutar lantarki. Wannan shine dalilin da ya sa wasu na’urorin ke da na’urorin da za a iya cirewa a cikin soket ɗin su, yayin da wasu ke buƙatar tazara tsakanin abin da ya keɓewa da na’urar ya zama ƙarami.

Duk wani babban sauri da na’urorin amfani da wutar lantarki yakamata a haɗa su gwargwadon iko don rage yawan wucewar wutar lantarki.

Ba tare da layin wutar lantarki ba, dogayen layukan wutar lantarki suna yin madauki tsakanin siginar da madauki, suna aiki azaman tushen radiation da kewaye.

Cabling forming madauki wanda baya wucewa ta hanyar kebul ɗin cibiyar sadarwa ɗaya ko wasu kebul ɗin ana kiransa madaidaicin madauki. Idan madauki yana wucewa ta kebul ɗin cibiyar sadarwa guda ɗaya, wasu hanyoyin suna yin madaidaicin madauki. A lokuta biyu, tasirin eriya (eriyar layi da eriyar zobe) na iya faruwa.