Ipakethe encinci yeMOSFETs

Xa i-MOSFET iqhagamshelwe kwindawo yebhasi kunye nendawo yokulayisha, iswitshi yecala lombane ophezulu iyasetyenziswa. Rhoqo i-P-channelIi-MOSFETszisetyenziswa kule topology, kwakhona uqwalaselo drive voltage. Ukumisela ireyithingi yangoku Inyathelo lesibini kukukhetha ukulinganisa kwangoku kweMOSFET. Ngokuxhomekeke kwisakhiwo sesekethe, eli nqanaba langoku kufuneka libe ngowona mzuzu uphezulu onokuwuthwala umthwalo phantsi kwazo zonke iimeko.

Ngokufanayo kwimeko yombane, umyili kufuneka aqinisekise ukuba okhethiweyoI-MOSFETinokumelana nolu mlinganiselo lwangoku, naxa inkqubo ivelisa imisinga ye-spike. Amatyala amabini angoku aqwalaselwayo yimowudi eqhubekayo kunye ne-pulse spikes. Le parameter ichazwe yi-FDN304P DATASHEET, apho i-MOSFET ikwimo ezinzileyo kwimodi yokuqhubela phambili, xa ikhoyo ngoku iqhubeka ihamba ngesixhobo.

I-Pulse spikes kuxa kukho i-surge enkulu (okanye i-spike) yangoku ehambayo kwisixhobo. Emva kokuba ubuninzi bangoku phantsi kwezi meko sele buchongiwe, yinto nje yokukhetha ngokuthe ngqo isixhobo esinokumelana nalo mbane uphezulu.

Emva kokukhetha i-current rated current, ilahleko yokuqhuba kufuneka nayo ibalwe. Ngokwesiqhelo, ii-MOSFETs azizozixhobo ezifanelekileyo kuba kukho ukulahleka kwamandla ngexesha lenkqubo yokuqhuba, ebizwa ngokuba yilahleko yokuqhuba.

I-MOSFET isebenza njengesixhathisi esiguquguqukayo xa "ivuliwe", njengoko kumiselwe yi-RDS(ON) yesixhobo, kwaye iyahluka kakhulu ngamaqondo obushushu. Ukutshatyalaliswa kwamandla kwesixhobo kungabalwa kwi-Iload2 x RDS (ON), kwaye ekubeni i-resistance on-resistance ihluka ngeqondo lokushisa, ukuchithwa kwamandla kuyahluka ngokulinganayo. Iphezulu i-voltage ye-VGS esetyenziswa kwi-MOSFET, encinci i-RDS (ON) iya kuba; ngokuchaseneyo nokuphezulu i-RDS(ON) iya kuba. Kumyili wenkqubo, kulapho urhwebo lungena khona ngokuxhomekeke kumbane wenkqubo. Kuyilo oluphathwayo, kulula (kwaye kuxhaphake ngakumbi) ukusebenzisa amandla ombane asezantsi, ngelixa kuyilo lwemizi-mveliso, kunokusetyenziswa amandla ombane aphezulu.

Qaphela ukuba i-RDS (ON) ukuxhathisa inyuka kancinane ngoku. Ukwahluka kwiiparitha ezahlukeneyo zombane ze-RDS (ON) ukuchasana kunokufumaneka kwiphepha ledatha yezobugcisa elinikezwe ngumenzi.

Ukumisela iiMfuno zeThermal Inyathelo elilandelayo ekukhetheni i-MOSFET kukubala iimfuno ze-thermal zesistim. Umyili kufuneka athathele ingqalelo iimeko ezimbini ezahlukeneyo, eyona meko imbi kunye neyenyani. Kucetyiswa ukuba ukubalwa kwemeko embi kakhulu kusetyenziswe, njengoko esi siphumo sibonelela ngomda omkhulu wokhuseleko kwaye siqinisekisa ukuba inkqubo ayiyi kuphumelela.

Kukwakho nemilinganiselo ethile ekufuneka uyiqaphele kwiI-MOSFETishiti yedatha; njengokumelana ne-thermal phakathi kwe-semiconductor junction yesixhobo esipakishiweyo kunye nokusingqongileyo okuzungezile, kunye nobushushu obuphezulu besiphambuka. Ubushushu be-junction yesixhobo bulingana nobushushu obuphezulu be-ambient kunye nemveliso yokumelana ne-thermal kunye nokuchithwa kwamandla (iqondo lokushisa elidibeneyo = ubushushu obuphezulu be-ambient + [ukumelana ne-thermal x ukuchithwa kwamandla]). Ukusuka kolu mlinganiso ubuninzi bokuchithwa kwamandla kwenkqubo kunokusombululeka, okuchazwa ngokulingana ne-I2 x RDS (ON).

Ekubeni umyili unqume ubuninzi bangoku oza kudlula kwisixhobo, i-RDS (ON) ingabalwa ngamaqondo okushisa ahlukeneyo. Kubalulekile ukuba uqaphele ukuba xa ujongene neemodeli ezilula ze-thermal, umyili kufuneka acinge kwakhona amandla okushisa e-semiconductor junction / i-enclosure yesixhobo kunye ne-enclosure / indalo; oko kukuthi, kuyafuneka ukuba ibhodi yesekethe eprintiweyo kunye nephakheji musa ukufudumala ngokukhawuleza.

Ngokwesiqhelo, i-PMOSFET, kuya kubakho i-parasitic diode ekhoyo, umsebenzi wediode kukuthintela uqhagamshelo lokubuyela umva komthombo, kwi-PMOS, inzuzo ngaphezulu kwe-NMOS kukuba i-voltage yokuvula inokuba yi-0, kunye nomahluko wombane phakathi kombane. I-voltage ye-DS ayininzi, ngelixa i-NMOS ikwimeko ifuna ukuba i-VGS ibe nkulu kunomgubasi, okuya kukhokelela kulawulo lombane ngokungenakuphepheka kunombane ofunekayo, kwaye kuya kubakho. ingxaki engeyomfuneko. I-PMOS ikhethwe njengokutshintsha kokulawula, kukho ezi zicelo zibini zilandelayo: isicelo sokuqala, i-PMOS yokwenza ukhetho lombane, xa i-V8V ikhona, ngoko i-voltage inikezelwa yi-V8V, i-PMOS iya kucima, i-VBAT ayiboneleli nge-voltage kwi-VSIN, kwaye xa i-V8V iphantsi, i-VSIN inikwe amandla yi-8V. Qaphela ukumiswa kwe-R120, isixhasi esitsala ngokuthe ngcembe amandla ombane esango ezantsi ukuqinisekisa ukulayita okufanelekileyo kwe-PMOS, ingozi karhulumente eyayanyaniswa nothintelo lwesango eliphezulu oluchazwe ngaphambili.

Imisebenzi ye-D9 kunye ne-D10 kukuthintela ukubuyisela amandla ombane, kwaye i-D9 inokushiywa. Kufuneka kuqatshelwe ukuba i-DS yesekethe iguqulwe ngokwenene, ukwenzela ukuba umsebenzi we-tube yokutshintsha awukwazi ukufezekiswa ngokuqhutyelwa kwe-diode eqhotyoshelweyo, ekufuneka iqatshelwe kwizicelo eziphathekayo. Kule sekethi, isignali yolawulo ye-PGC ilawula ukuba i-V4.2 inika amandla kwi-P_GPRS. Le sekethe, umthombo kunye neetheminali zombhobho aziqhagamshelwanga kwicala elichaseneyo, i-R110 kunye ne-R113 ikhona ngengqiqo yokuba isango lolawulo le-R110 langoku alikho likhulu kakhulu, i-R113 yokulawula isango eliqhelekileyo, i-R113 yokutsalwa phezulu, njenge-PMOS, kodwa kwakhona. kunokubonwa njengokutsalwa kwisibonakaliso solawulo, xa izikhonkwane zangaphakathi ze-MCU kunye nokutsalwa, oko kukuthi, imveliso ye-drain evulekileyo xa imveliso ingayiqhubi i-PMOS, ngeli xesha, i Iza kufuna amandla ombane angaphandle ukunika ukutsalwa, ngoko ke i-resistor R113 idlala iindima ezimbini. I-r110 inokuba ncinane, ukuya kwi-100 ohms ingaba.

Ii-MOSFET zephakheji ezincinci zinendima eyodwa ekufuneka ziyidlalile.