MOSFET Package Switching Tube Selection ndi Zithunzi Zozungulira

Gawo loyamba ndikusankhaZithunzi za MOSFET, yomwe imabwera m'mitundu iwiri ikuluikulu: N-channel ndi P-channel. M'makina amagetsi, ma MOSFET amatha kuganiziridwa ngati ma switch amagetsi. Mphamvu yabwino ikawonjezeredwa pakati pa chipata ndi gwero la N-channel MOSFET, kusintha kwake kumachita. Panthawi yoyendetsa, magetsi amatha kuyenda kudzera pakusintha kuchokera kukhetsa kupita kugwero. Pali kukana kwamkati pakati pa kukhetsa ndi gwero lotchedwa on-resistance RDS(ON). Ziyenera kuonekeratu kuti chipata cha MOSFET ndi malo okwera kwambiri, choncho magetsi amawonjezeredwa pachipata. Uku ndiko kukana kwa nthaka komwe chipatacho chimalumikizidwa nacho mu chithunzi chozungulira chomwe chikuwonetsedwa pambuyo pake. Ngati chipata chikasiyidwa chikulendewera, chipangizocho sichingagwire ntchito monga momwe chinapangidwira ndipo chikhoza kuyatsa kapena kuzimitsa nthawi zosayenerera, zomwe zimapangitsa kuti mphamvu iwonongeke mu dongosolo. Pamene magetsi pakati pa gwero ndi chipata ndi zero, chosinthira chimazimitsa ndipo magetsi amasiya kuyenda pa chipangizocho. Ngakhale kuti chipangizochi chazimitsidwa panthawiyi, palinso kachidutswa kakang'ono kamene kamatchedwa leakage current, kapena IDSS.

Gawo 1: Sankhani N-channel kapena P-channel

Gawo loyamba pakusankha chipangizo choyenera cha kapangidwe kake ndikusankha kugwiritsa ntchito njira ya N kapena P-channel MOSFET. mu ntchito mmene mphamvu, pamene MOSFET ndi pansi ndipo katundu chikugwirizana ndi thunthu voteji, kuti MOSFET amapanga otsika voteji mbali lophimba. M'mbali yotsika yamagetsi, njira ya NMOSFETziyenera kugwiritsidwa ntchito chifukwa choganizira mphamvu yamagetsi yomwe ikufunika kuzimitsa kapena kuyatsa chipangizocho. MOSFET ikalumikizidwa ndi basi ndipo katunduyo wakhazikika, chosinthira chamagetsi chapamwamba chiyenera kugwiritsidwa ntchito. P-channel MOSFET nthawi zambiri imagwiritsidwa ntchito mu topology iyi, komanso pakuganizira za ma voltage drive.

Gawo 2: Dziwani mavoti apano

Gawo lachiwiri ndikusankha mavoti apano a MOSFET. Kutengera kapangidwe ka dera, mlingo wapanowu uyenera kukhala wokwera kwambiri womwe katunduyo ungathe kupirira nthawi zonse. Mofanana ndi vuto la magetsi, wopangayo ayenera kuonetsetsa kuti MOSFET yosankhidwa ikhoza kupirira izi, ngakhale pamene makina akupanga mafunde a spike. Milandu iwiri yomwe ikuganiziridwayi ndi yopitilira komanso ma pulse spikes. Izi zakhazikitsidwa pa FDN304P chubu DATASHEET monga kalozera ndipo magawo akuwonetsedwa pachithunzichi:

Mumayendedwe opitilira, MOSFET imakhala yokhazikika, pomwe pano ikuyenda mosalekeza kudzera pa chipangizocho. Ma pulse spikes ndi pamene pali mafunde ambiri (kapena spike current) akuyenda kudzera pa chipangizocho. Pamene mphamvu yapamwamba pansi pazimenezi yatsimikiziridwa, ndi nkhani yosankha mwachindunji chipangizo chomwe chingathe kupirira pakali pano.

Pambuyo posankha oveteredwa panopa, muyeneranso kuwerengera conduction imfa. M'malo mwake, aMOSFETsi chipangizo choyenera, chifukwa mumayendedwe oyendetsa padzakhala kutaya mphamvu, komwe kumatchedwa kutaya kwa conduction. MOSFET mu "pa" ngati kukana kosinthika, komwe kumatsimikiziridwa ndi chipangizo cha RDS (ON), komanso kutentha ndi kusintha kwakukulu. Kutaya mphamvu kwa chipangizochi kumatha kuwerengedwa kuchokera ku Iload2 x RDS (ON), ndipo popeza kukana kumasiyana ndi kutentha, kutayika kwa mphamvu kumasiyana mosiyanasiyana. Kukwera kwa VGS komwe kumagwiritsidwa ntchito ku MOSFET, RDS (ON) idzakhala yaying'ono; m'malo mwake, RDS (ON) idzakhala yokwera. Kwa wopanga makina, apa ndipamene tradeoffs imagwira ntchito kutengera mphamvu yamagetsi. Pazojambula zonyamula, ndizosavuta (komanso zofala) kugwiritsa ntchito ma voltages otsika, pomwe pamapangidwe a mafakitale, ma voltages apamwamba angagwiritsidwe ntchito. Dziwani kuti kukana kwa RDS(ON) kumakwera pang'ono ndi pano. Kusiyanasiyana kwamagawo osiyanasiyana amagetsi a RDS(ON) resistor atha kupezeka muzolemba zaukadaulo zomwe zimaperekedwa ndi wopanga.

Khwerero 3: Dziwani Zofunikira Zotentha

Chotsatira posankha MOSFET ndikuwerengera zofunikira za kutentha kwa dongosolo. Wopangayo ayenera kuganizira zochitika ziwiri zosiyana, zoyipitsitsa komanso zowona. Kuwerengera kwa zochitika zoipitsitsa kumalimbikitsidwa chifukwa chotsatirachi chimapereka malire ochuluka a chitetezo ndikuonetsetsa kuti dongosololi silidzalephera. Palinso miyeso ina yofunika kudziwa pa pepala la data la MOSFET; monga kukana kwamafuta pakati pa mphambano ya semiconductor ya chipangizo chopakidwa ndi chilengedwe, komanso kutentha kwakukulu kwa mphambano.

Kutentha kwapamtunda kwa chipangizocho ndi kofanana ndi kutentha kwakukulu kozungulira kuphatikizapo chinthu cha kukana kutentha ndi kutaya mphamvu (kutentha kwapakati = kutentha kwakukulu kozungulira + [kukana kutentha × kutaya mphamvu]). Kuchokera pa equation iyi mphamvu yochuluka yotaya mphamvu ya dongosolo ikhoza kuthetsedwa, yomwe ndi tanthauzo lofanana ndi I2 x RDS (ON). Popeza ogwira ntchito atsimikiza kuchuluka kwamakono komwe kudzadutsa pa chipangizocho, RDS (ON) ikhoza kuwerengedwa kutentha kosiyana. Ndikofunika kuzindikira kuti pochita ndi zitsanzo zosavuta zotentha, wopanga ayenera kuganiziranso mphamvu ya kutentha kwa semiconductor junction / device case ndi mlandu / chilengedwe; mwachitsanzo, pamafunika kuti bolodi losindikizidwa ndi phukusi zisatenthe nthawi yomweyo.

Nthawi zambiri, PMOSFET, padzakhala parasitic diode yomwe ilipo, ntchito ya diode ndikuletsa kulumikizana kwa gwero-drain reverse, kwa PMOS, mwayi pa NMOS ndikuti mphamvu yake yoyatsa imatha kukhala 0, komanso kusiyana kwamagetsi pakati pa DS voteji si zambiri, pamene NMOS pa chikhalidwe amafuna kuti VGS kukhala wamkulu kuposa pakhomo, zomwe zidzachititsa kuti mphamvu voteji ndi mosalephera kuposa voteji chofunika, ndipo padzakhala zovuta zosafunikira. PMOS imasankhidwa ngati chosinthira chowongolera pazotsatira ziwiri zotsatirazi:

Kutentha kwapamtunda kwa chipangizocho ndi kofanana ndi kutentha kwakukulu kozungulira kuphatikizapo chinthu cha kukana kutentha ndi kutaya mphamvu (kutentha kwapakati = kutentha kwakukulu kozungulira + [kukana kutentha × kutaya mphamvu]). Kuchokera pa equation iyi mphamvu yochuluka yotaya mphamvu ya dongosolo ikhoza kuthetsedwa, yomwe ndi tanthauzo lofanana ndi I2 x RDS (ON). Popeza wopanga adatsimikiza kuchuluka kwamakono komwe kudzadutsa pa chipangizocho, RDS(ON) imatha kuwerengedwa kutentha kosiyanasiyana. Ndikofunika kuzindikira kuti pochita ndi zitsanzo zosavuta zotentha, wopanga ayenera kuganiziranso mphamvu ya kutentha kwa semiconductor junction / device case ndi mlandu / chilengedwe; mwachitsanzo, pamafunika kuti bolodi losindikizidwa ndi phukusi zisatenthe nthawi yomweyo.

Nthawi zambiri, PMOSFET, padzakhala parasitic diode yomwe ilipo, ntchito ya diode ndikuletsa kulumikizana kwa gwero-drain reverse, kwa PMOS, mwayi pa NMOS ndikuti mphamvu yake yoyatsa imatha kukhala 0, komanso kusiyana kwamagetsi pakati pa DS voteji si zambiri, pamene NMOS pa chikhalidwe amafuna kuti VGS kukhala wamkulu kuposa pakhomo, zomwe zidzachititsa kuti mphamvu voteji ndi mosalephera kuposa voteji chofunika, ndipo padzakhala zovuta zosafunikira. PMOS imasankhidwa ngati chosinthira chowongolera pazotsatira ziwiri zotsatirazi:

Kuyang'ana dera ili, chizindikiro chowongolera PGC chimawongolera ngati V4.2 ikupereka mphamvu kwa P_GPRS. Dera ili, magwero ndi ma terminals akukhetsa samalumikizidwa kumbuyo, R110 ndi R113 alipo m'lingaliro lakuti R110 control gate panopa si yayikulu kwambiri, R113 imayang'anira chipata chanthawi zonse, R113 kukoka mpaka kumtunda, kuyambira PMOS. , komanso amatha kuwoneka ngati kukoka pa siginecha yowongolera, pomwe zikhomo zamkati za MCU ndi kukoka, ndiko kuti, kutulutsa kwamadzi otseguka pomwe zotuluka zimatseguka, ndipo sindingathe kuthamangitsa PMOS, panthawiyi, ndikofunikira kuti voteji yakunja iperekedwe, kotero resistor R113 imagwira ntchito ziwiri. Idzafunika mphamvu yakunja kuti ipereke chikoka, kotero resistor R113 imagwira ntchito ziwiri. R110 ikhoza kukhala yaying'ono, mpaka 100 ohms imathanso.