MOSFET Ukukhetha Amaphuzu

Ukukhetha kweI-MOSFETkubaluleke kakhulu, ukukhetha okubi kungase kuthinte ukusetshenziswa kwamandla kwesekethe yonke, ukuqonda ama-nuances wezingxenye ezahlukene ze-MOSFET kanye nemingcele kumasekethe ahlukene okushintshwa kungasiza onjiniyela ukugwema izinkinga eziningi, okulandelayo ezinye zezincomo zikaGuanhua Weiye ngokukhethwa kwama-MOSFET.

Okokuqala, i-P-channel ne-N-channel

Isinyathelo sokuqala ukunquma ukusetshenziswa kwe-N-channel noma i-P-channel MOSFETs. ekusetshenzisweni kwamandla, lapho umhlabathi we-MOSFET, nomthwalo uxhunywe ku-voltage ye-trunk, i-I-MOSFETyakha iswishi eseceleni ene-voltage ephansi. Ekushintsheni ohlangothini lwe-voltage ephansi, ama-MOSFET wesiteshi se-N ngokuvamile asetshenziswa, okuwukucatshangelwa kwamandla kagesi adingekayo ukuze ucishwe noma uvule idivayisi. Lapho i-MOSFET ixhunywe endaweni yebhasi kanye nendawo yokulayisha, kusetshenziswa iswishi ye-voltage ephezulu. Ama-MOSFET esiteshi se-P avame ukusetshenziswa, ngenxa yokucatshangelwa kwe-voltage drive. Ukuze ukhethe izingxenye ezifanele zohlelo lokusebenza, kubalulekile ukucacisa i-voltage edingekayo ukuze ushayele idivayisi nokuthi kulula kangakanani ukuyisebenzisa ekwakhiweni. Isinyathelo esilandelayo ukunquma isilinganiso se-voltage esidingekayo, noma umthamo omkhulu we-voltage leyo ingxenye engawuthwala. Uma siphezulu isilinganiso sikagesi, izindleko zedivayisi ziphezulu. Empeleni, isilinganiso se-voltage kufanele sibe sikhulu kunomthamo we-trunk noma webhasi. Lokhu kuzonikeza ukuvikeleka okwanele ukuze i-MOSFET ingaphumeleli. Ekukhetheni i-MOSFET, kubalulekile ukunquma umthamo omkhulu we-voltage ongabekezelelwa kusuka ku-drain kuya emthonjeni, okungukuthi, i-VDS ephezulu, ngakho-ke kubalulekile ukwazi ukuthi i-voltage ephezulu i-MOSFET engakwazi ukumelana nayo iyahlukahluka ngokuya ngezinga lokushisa. Abaklami badinga ukuhlola ububanzi be-voltage kulo lonke uhla lokushisa lokusebenza. I-voltage elinganiselwe idinga ukuba nemajini eyanele ukumboza lobu bubanzi ukuze kuqinisekiswe ukuthi umjikelezo awehluleki. Ngaphezu kwalokho, ezinye izici zokuphepha zidinga ukucatshangelwa njengama-voltage enziwayo.

Okwesibili, nquma isilinganiso samanje

Isilinganiso samanje se-MOSFET sincike esakhiweni sesekhethi. Isilinganiso samanje siwumkhawulo wamanje umthwalo ongamelana nawo ngaphansi kwazo zonke izimo. Ngokufanayo nekesi le-voltage, umklami udinga ukwenza isiqiniseko sokuthi i-MOSFET ekhethiwe iyakwazi ukuthwala lesi samanje esilinganiselwe, ngisho noma uhlelo lukhiqiza i-spike current. Izimo ezimbili zamanje okufanele zicatshangelwe imodi eqhubekayo kanye nama-pulse spikes. i-MOSFET isesimweni esingaguquki kumodi yokuqhuba eqhubekayo, lapho okwamanje kudlula ngokuqhubekayo ocingweni. Ama-pulse spikes abhekisela enanini elikhulu lama-surges (noma ama-spikes of current) ageleza ocingweni, lapho-ke, uma inani eliphezulu lamanje selinqunyiwe, kumane kuyindaba yokukhetha ngokuqondile idivayisi engakwazi ukumelana nalesi silinganiso esiphezulu.

Ngemva kokukhetha i-current rated, ukulahlekelwa kokuqhuba nakho kubalwa. Ezimweni ezithile,I-MOSFETakuzona izingxenye ezifanelekile ngenxa yokulahlekelwa kukagesi okwenzeka ngesikhathi senqubo yokuqhuba, lokho okubizwa ngokuthi ukulahlekelwa kwe-conduction. Uma "ivuliwe", i-MOSFET isebenza njengesinqamuleli esiguquguqukayo, esinqunywa i-RDS(ON) yedivayisi futhi sishintsha kakhulu ngezinga lokushisa. Ukulahlekelwa kwamandla kwedivayisi kungabalwa kusukela ku-Iload2 x RDS(ON), futhi njengoba ukumelana nokushisa kushintshana nezinga lokushisa, ukulahlekelwa kwamandla kuyehluka ngokulinganayo. Uma iphezulu i-voltage VGS esetshenziswa ku-MOSFET, i-RDS(ON) yehla; ngokuphambene, ukuphakama kwe-RDS(ON). Kumklami wesistimu, kulapho uhwebo luqala khona ukusebenza ngokuya ngevolthi yesistimu. Emiklamo ephathekayo, ama-voltage aphansi alula (futhi avame kakhulu), kuyilapho emiklamo yezimboni, ama-voltage aphezulu angasetshenziswa. Qaphela ukuthi ukumelana ne-RDS(ON) kukhuphuka kancane ngokwamanje.

Ubuchwepheshe bunomthelela omkhulu ezicini zengxenye, futhi obunye ubuchwepheshe buvame ukuphumela ekwenyukeni kwe-RDS(ON) lapho kukhushulwa i-VDS ephezulu. Ngobuchwepheshe obunjalo, ukukhuphuka kosayizi we-wafer kuyadingeka uma i-VDS ne-RDS(ON) zizokwehliswa, ngaleyo ndlela kukhuliswe usayizi wephakheji ohambisana nayo kanye nezindleko zokuthuthukiswa ezihambisanayo. Kunenqwaba yobuchwepheshe embonini obuzama ukulawula ukukhuphuka kosayizi wama-wafer, obubaluleke kakhulu obuchwephesha be-trench kanye nobuchwepheshe bebhalansi yokushaja. Kubuchwepheshe bomsele, umsele ojulile ushunyekwa ku-wafer, ngokuvamile ubekelwe ama-voltage aphansi, ukuze kuncishiswe i-RDS(ON) yokungamelani.

III. Nquma izidingo zokukhipha ukushisa

Isinyathelo esilandelayo ukubala izidingo ezishisayo zesistimu. Kudingeka kubhekwe izimo ezimbili ezihlukene, icala elibi kakhulu kanye nelangempela. I-TPV incoma ukubalwa kwemiphumela yesimo esibi kakhulu, njengoba lesi sibalo sinikeza umkhawulo omkhulu wokuphepha futhi siqinisekisa ukuthi isistimu ngeke ihluleke.

IV. Ishintsha Ukusebenza

Ekugcineni, ukusebenza kokushintsha kwe-MOSFET. Kunamapharamitha amaningi athinta ukusebenza kokushintsha, okubalulekile yisango/ukukhipha amanzi, isango/umthombo kanye ne-drain/source capacitance. Lawa mandla enza ukulahlekelwa kokushintsha engxenyeni ngenxa yesidingo sokuwakhokhisa njalo lapho eshintshwa. Ngenxa yalokho, ijubane lokushintsha le-MOSFET liyancipha futhi ukusebenza kahle kwedivayisi kuncipha. Ukuze kubalwe ukulahlekelwa okuphelele kudivayisi ngesikhathi sokushintsha, umklami udinga ukubala ukulahlekelwa ngesikhathi sokuvula (i-Eon) kanye nokulahlekelwa phakathi nokucisha (Eoff). Lokhu kungavezwa ngezibalo ezilandelayo: Psw = (Eon + Eoff) x ukushintsha imvamisa. Futhi ukushajwa kwesango (Qgd) kunomthelela omkhulu ekushintsheni ukusebenza.