In ngesivinini PCB ukuklama, ukusetshenziswa kwesignali ehlukile (Isiginali ye-DIFferential) iya ngokuya ikhula, futhi isignali ebaluleke kakhulu kumjikelezo ivame ukuklanywa ngesakhiwo esihlukile. Kungani kunjalo? Uma kuqhathaniswa nomzila wesiginali onesiphelo esisodwa esijwayelekile, amasiginali ahlukene anezinzuzo zekhono eliqinile lokulwa nokuphazamiseka, ukucindezela okusebenzayo kwe-EMI, kanye nokuma kwesikhathi okunembayo.

Izidingo zocingo ze-PCB zesignali ehlukile

Ebhodini lesifunda, imikhondo ehlukene kufanele ibe imigqa emibili yobude obulinganayo, ububanzi obulinganayo, ukusondelana, futhi ezingeni elifanayo.

1. Ubude obulinganayo: Ubude obulinganayo busho ukuthi ubude bemigqa emibili kufanele bube bude ngangokunokwenzeka, ukuze kuqinisekiswe ukuthi izimpawu ezimbili ezihlukene zigcina ama-polarity aphikisanayo ngaso sonke isikhathi. Yehlisa izingxenye zemodi evamile.

2. Ububanzi obulinganayo nebanga elilinganayo: Ububanzi obulinganayo busho ukuthi ububanzi beminonjana yezimpawu ezimbili budinga ukugcinwa bufana, futhi ibanga elilinganayo lisho ukuthi ibanga phakathi kwezintambo ezimbili kufanele ligcinwe lingashintshi futhi lihambisana.

3. Ushintsho oluncane lwe-impedance: Lapho uklama i-PCB enezimpawu ezihlukanisayo, enye yezinto ezibaluleke kakhulu ukuthola ukuthikamezeka okuhlosiwe kwesicelo, bese uhlela ukubhanqwa kokwahlukana ngokufanele. Ngaphezu kwalokho, gcina ushintsho lwe-impedance luncane ngangokunokwenzeka. Ukuthikamezeka komugqa ohlukile kuncike ezintweni ezifana nobubanzi bokulandelela, ukuhlangana kokulandelela, ukujiya kwethusi, nokokusebenza kwe-PCB nokupakisha. Uma uzama ukugwema noma yini eshintsha i-impedance ye-pair ehlukile, cabangela ngayinye yazo.

Ukungaqondi kahle okujwayelekile ekwakhiweni kwesignali ehlukile kwe-PCB

Ukungaqondi kahle 1: Kukholakala ukuthi isignali ehlukile ayidingi indiza ephansi njengendlela yokubuya, noma ukuthi imikhondo ehlukene inikeza indlela yokubuya komunye nomunye.

Isizathu salokhu kungaqondi kahle ukuthi badidwe izenzakalo ezikha phezulu, noma indlela yokudlulisa isignali ngesivinini esiphezulu ayijulile ngokwanele. Amasekhethi ahlukene awazwani nokubhampa komhlaba okufanayo nezinye izimpawu zomsindo ezingase zibe khona emandleni nasezindizeni eziphansi. Ukukhanselwa kokubuyisela ingxenye yendiza yaphansi akusho ukuthi isifunda esihlukanisayo asisebenzisi indiza yereferensi njengendlela yokubuya kwesignali. Eqinisweni, ekuhlaziyweni kokubuyiselwa kwesignali, indlela yokuhlukanisa izintambo kanye nezintambo ezijwayelekile ezinomkhawulo owodwa ziyafana, okungukuthi, amasignali amafrikhwensi ahlala egeleza kabusha ku-loop nge-inductance encane kakhulu. Umehluko omkhulu kakhulu ukuthi ngaphezu kokuhlanganisa phansi, umugqa wokuhlukanisa nawo unokuhlanganisa okuhlangene. Iluphi uhlobo lokuhlanganisa oluqinile, futhi iyiphi eba indlela eyinhloko yokubuya.

Ekwakhiweni kwesekethe ye-PCB, ukuhlangana phakathi kokulandela okuhlukile ngokuvamile kuncane, ngokuvamile kubala kuphela i-10-20% yedigri yokuhlanganisa, futhi ngaphezulu ukuhlangana phansi, ngakho-ke indlela eyinhloko yokubuya yokulandelela okuhlukile isekhona phansi. indiza . Uma kunokungaqhubeki endizeni yaphansi, ukuhlangana phakathi kweminonjana ehlukene endaweni ngaphandle kwendiza eyinkomba kuzohlinzeka ngendlela eyinhloko yokubuya, nakuba ukungaqhubeki kwendiza eyinkomba akunawo umthelela emithonjeni ehlukene endaweni evamile enesiphetho esisodwa. imikhondo Ibucayi, kodwa isazonciphisa ikhwalithi yesiginali yokuhlukanisa futhi ikhulise i-EMI, okufanele igwenywe ngangokunokwenzeka.

Ngaphezu kwalokho, abanye abaklami bakholelwa ukuthi indiza eyinkomba ngaphansi komkhondo ohlukile ingasuswa ukuze kucindezelwe ingxenye yesiginali yemodi evamile ekudluliseni okuhlukile. Nokho, le ndlela ayifiseleki ngokombono. Indlela yokulawula impedance? Ukunganikezi iluphu ye-impedance yaphansi yesiginali yemodi evamile kuzodala imisebe ye-EMI nakanjani. Le ndlela yenza umonakalo omkhulu kunokuhle.

Ukungaqondi kahle 2: Kukholakala ukuthi ukugcina isikhala esilinganayo kubaluleke kakhulu kunokufanisa ubude bomugqa.

Kusakhiwo sangempela se-PCB, ngokuvamile akwenzeki ukuhlangabezana nezidingo zedizayini ehlukile ngesikhathi esisodwa. Ngenxa yobukhona bezinto ezinjengokusabalalisa amaphini, i-vias, nesikhala sezintambo, inhloso yokufanisa ubude bomugqa kufanele ifinyelelwe ngokusonteka okufanele, kodwa umphumela kufanele ube ukuthi ezinye izindawo zokubhangqa okuhlukile azikwazi ukuhambisana. Umthetho obaluleke kakhulu ekwakhiweni kokulandela okuhlukile kwe-PCB ubude bomugqa ofanayo. Eminye imithetho ingaphathwa ngendlela evumelana nezimo ngokuya ngezidingo zokuklama kanye nezicelo zangempela.

Ukungaqondi kahle 3: Cabanga ukuthi izintambo ezihlukanisayo kumele zibe seduze kakhulu.

Ukugcina iminonjana ehlukene iseduze akuyona into engaphezu kokuthuthukisa ukuhlangana kwayo, okungagcini nje ukuthuthukisa ukungatheleleki emsindweni, kodwa futhi kusebenzise ngokugcwele i-polarity ephambene yenkundla kazibuthe ukuze kunqandwe ukuphazamiseka kukazibuthe ezweni langaphandle. Nakuba le ndlela inenzuzo kakhulu ezimweni eziningi, ayiphelele. Uma singaqinisekisa ukuthi zivikelwe ngokugcwele ekuphazamisekeni kwangaphandle, ngakho-ke akudingeki sisebenzise ukuhlanganisa okuqinile ukuze sizuze ukulwa nokuphazamiseka. Futhi inhloso yokucindezela i-EMI.

Singakuqinisekisa kanjani ukuhlukaniswa okuhle nokuvikela iminonjana ehlukahlukene? Ukwandisa isikhala ngokunye ukulandelelwa kwesignali kungenye yezindlela eziyisisekelo. Amandla kazibuthe kagesi ancipha ngesikwele sebanga. Ngokuvamile, lapho isikhala somugqa sidlula izikhathi ezi-4 ububanzi bomugqa, ukuphazamiseka phakathi kwawo kuba buthaka kakhulu. Inganakwa.