MOSFET chidziwitso choyambirira ndi kugwiritsa ntchito

Chifukwa chake njira yochepetseraZithunzi za MOSFETsizikugwiritsidwa ntchito, sizikulimbikitsidwa kuti zifike pansi pake.

Kwa ma MOSFET awiriwa, NMOS imagwiritsidwa ntchito kwambiri. Chifukwa chake ndi chakuti pa-kukana ndi yaying'ono komanso yosavuta kupanga. Chifukwa chake, NMOS nthawi zambiri imagwiritsidwa ntchito posinthira magetsi ndi ma drive drive. Pachiyambi chotsatira, NMOS imagwiritsidwa ntchito kwambiri.

Pali mphamvu ya parasitic pakati pa zikhomo zitatu za MOSFET. Izi sizomwe timafunikira, koma zimayambitsidwa ndi kuchepa kwa njira zopangira. Kukhalapo kwa mphamvu ya parasitic kumapangitsa kuti zikhale zovuta kwambiri popanga kapena kusankha dera loyendetsa, koma palibe njira yopewera. Tidzafotokoza mwatsatanetsatane pambuyo pake.

Pali parasitic diode pakati pa kukhetsa ndi gwero. Izi zimatchedwa diode ya thupi. Diode iyi ndiyofunikira kwambiri pakuyendetsa katundu wowonjezera (monga ma mota). Mwa njira, diode ya thupi imangopezeka mu MOSFET imodzi ndipo nthawi zambiri sapezeka mkati mwa chipangizo chophatikizika.

 

2. MOSFET conduction makhalidwe

Kuyendetsa kumatanthauza kuchita ngati chosinthira, chomwe chili chofanana ndi kusinthaku kutsekedwa.

Makhalidwe a NMOS ndikuti imayatsidwa pomwe Vgs ndi yayikulu kuposa mtengo wina. Ndioyenera kugwiritsidwa ntchito pamene gwero lakhazikitsidwa (otsika-mapeto pagalimoto), bola ngati chipata voteji kufika 4V kapena 10V.

Makhalidwe a PMOS ndikuti idzayatsa pamene Vgs ili yochepa kuposa mtengo wina, womwe ndi woyenera pazochitika zomwe gwero limagwirizanitsidwa ndi VCC (high-end drive). Komabe, ngakhalePMOSangagwiritsidwe ntchito mosavuta ngati dalaivala mkulu-mapeto, NMOS kawirikawiri ntchito madalaivala mkulu-mapeto chifukwa chachikulu pa-kukana, kukwera mtengo, ndi ochepa m'malo mitundu.

 

3. MOS kusintha chubu kutaya

Kaya ndi NMOS kapena PMOS, pali kukana pambuyo poyatsidwa, kotero zapano zidzawononga mphamvu pakukana uku. Gawo ili la mphamvu zomwe zimagwiritsidwa ntchito limatchedwa conduction loss. Kusankha MOSFET yokhala ndi kukana pang'ono kumachepetsa kutayika kwa conduction. Masiku ano mphamvu zochepa za MOSFET pa-kukana nthawi zambiri zimakhala pafupifupi mamiliyoni makumi ambiri, ndipo palinso mamiliyoni angapo.

MOSFET ikayatsidwa ndikuzimitsidwa, siyenera kumaliza nthawi yomweyo. Mpweya wodutsa pa MOS umakhala ndi njira yocheperako, ndipo kuthamanga kwa madzi kumawonjezeka. Panthawi imeneyi, aZithunzi za MOSFETkutayika kumachitika chifukwa cha magetsi ndi magetsi, omwe amatchedwa switching loss. Nthawi zambiri zotayika zosinthira zimakhala zazikulu kwambiri kuposa kutayika kwa conduction, ndipo kufulumira kwakusintha pafupipafupi, kumabweretsa kutayika kwakukulu.

Zopangidwa ndi magetsi komanso zamakono panthawi yoyendetsa ndi zazikulu kwambiri, zomwe zimayambitsa kutayika kwakukulu. Kufupikitsa nthawi yosinthira kungachepetse kutayika panthawi iliyonse ya conduction; kuchepetsa kusintha kwafupipafupi kungachepetse chiwerengero cha masinthidwe pa nthawi ya unit. Njira zonsezi zimatha kuchepetsa kutayika kwa kusintha.

The waveform pamene MOSFET yatsegulidwa. Zitha kuwoneka kuti chopangidwa ndi voteji ndi chapano panthawi ya conduction ndi yayikulu kwambiri, ndipo kutayika komwe kumayambitsa kumakhalanso kwakukulu kwambiri. Kuchepetsa nthawi yosinthira kungachepetse kutayika panthawi iliyonse ya conduction; kuchepetsa kusintha kwafupipafupi kungachepetse chiwerengero cha masinthidwe pa nthawi ya unit. Njira zonsezi zimatha kuchepetsa kutayika kwa kusintha.

 

4. MOSFET woyendetsa

Poyerekeza ndi ma transistors a bipolar, amakhulupirira kuti palibe chapano chomwe chimafunikira kuyatsa MOSFET, bola mphamvu ya GS ili yokwera kuposa mtengo wina. Izi ndizosavuta, koma timafunikiranso liwiro.

Zitha kuwoneka mu kapangidwe ka MOSFET kuti pali mphamvu ya parasitic pakati pa GS ndi GD, ndipo kuyendetsa kwa MOSFET ndiko kwenikweni kulipiritsa ndi kutulutsa capacitor. Kulipiritsa capacitor kumafuna panopa, chifukwa capacitor akhoza kuonedwa ngati dera lalifupi panthawi yolipiritsa, kotero kuti nthawi yomweyo idzakhala yaikulu. Choyambirira chomwe muyenera kulabadira posankha / kupanga dalaivala wa MOSFET ndi kuchuluka kwapanthawi kochepa komwe kungapereke. .

Chinthu chachiwiri choyenera kukumbukira ndi chakuti NMOS, yomwe imagwiritsidwa ntchito kwambiri poyendetsa galimoto, imayenera kuti magetsi a geti akhale aakulu kuposa magetsi oyambira akayatsidwa. Pamene MOSFET yoyendetsedwa kwambiri ikayatsidwa, mphamvu yamagetsi imakhala yofanana ndi voteji ya drain (VCC), kotero kuti magetsi a pachipata ndi 4V kapena 10V kuposa VCC panthawiyi. Ngati mukufuna kupeza voteji yokulirapo kuposa VCC pamakina omwewo, mufunika dera lowonjezera lapadera. Madalaivala ambiri amagalimoto amakhala ndi mapampu ophatikizika opangira. Tiyenera kuzindikira kuti capacitor yoyenera yakunja iyenera kusankhidwa kuti ipeze nthawi yochepa yokwanira yoyendetsa MOSFET.

 

4V kapena 10V yotchulidwa pamwambapa ndi magetsi oyatsa a MOSFET omwe amagwiritsidwa ntchito nthawi zambiri, ndipo ndithudi malire ena ayenera kuloledwa panthawi ya mapangidwe. Ndipo mphamvu yamagetsi ikukwera, kuthamanga kwa conduction kumathamanga komanso kumachepetsa kukana kwa conduction. Tsopano pali ma MOSFET okhala ndi ma voltages ang'onoang'ono omwe amagwiritsidwa ntchito m'magawo osiyanasiyana, koma mumagetsi amagetsi a 12V, nthawi zambiri 4V conduction ndiyokwanira.

 

Pamayendedwe oyendetsa a MOSFET ndi kutayika kwake, chonde onani za Microchip's AN799 Matching MOSFET Drivers to MOSFETs. Ndilo mwatsatanetsatane, kotero sindilemba zambiri.

 

Zopangidwa ndi magetsi komanso zamakono panthawi yoyendetsa ndi zazikulu kwambiri, zomwe zimayambitsa kutayika kwakukulu. Kuchepetsa nthawi yosinthira kungachepetse kutayika panthawi iliyonse ya conduction; kuchepetsa kusintha kwafupipafupi kungachepetse chiwerengero cha masinthidwe pa nthawi ya unit. Njira zonsezi zimatha kuchepetsa kutayika kwa kusintha.

MOSFET ndi mtundu wa FET (winawo ndi JFET). Itha kupangidwa kukhala njira yolimbikitsira kapena kutsitsa, P-channel kapena N-channel, mitundu inayi yonse. Komabe, njira yowonjezera-N-channel MOSFET ndiyomwe imagwiritsidwa ntchito. ndi mtundu wa P-channel MOSFET, kotero NMOS kapena PMOS nthawi zambiri amatchula mitundu iwiriyi.

 

5. MOSFET ntchito dera?

Chofunikira kwambiri cha MOSFET ndi mawonekedwe ake abwino osinthira, motero amagwiritsidwa ntchito kwambiri m'mabwalo omwe amafunikira ma switch amagetsi, monga kusinthira magetsi ndi ma drive amagalimoto, komanso kuyatsa kuyatsa.

 

Madalaivala amasiku ano a MOSFET ali ndi zofunika zingapo zapadera:

1. Kugwiritsa ntchito magetsi otsika

Mukamagwiritsa ntchito magetsi a 5V, ngati chikhalidwe cha totem pole chimagwiritsidwa ntchito panthawiyi, popeza transistor ikhale ndi dontho lamagetsi pafupifupi 0.7V, voteji yomaliza yomwe imagwiritsidwa ntchito pachipata ndi 4.3V yokha. Panthawiyi, timasankha mphamvu yachipata chodziwika bwino

Pali chiopsezo china mukamagwiritsa ntchito 4.5V MOSFET. Vuto lomwelo limapezekanso mukamagwiritsa ntchito 3V kapena magetsi ena otsika.

2. Wide voltage ntchito

Mphamvu yolowera simtengo wokhazikika, idzasintha ndi nthawi kapena zinthu zina. Kusintha kumeneku kumapangitsa kuti magetsi oyendetsa operekedwa ndi dera la PWM kupita ku MOSFET akhale osakhazikika.

Pofuna kupanga ma MOSFET kukhala otetezeka pansi pa ma voltages apamwamba, ma MOSFET ambiri ali ndi zowongolera magetsi kuti achepetse mphamvu yamagetsi amagetsi. Pamenepa, mphamvu yoyendetsa yomwe yaperekedwa ikadutsa mphamvu yamagetsi yamagetsi, imayambitsa kugwiritsa ntchito mphamvu zambiri.

Nthawi yomweyo, ngati mungogwiritsa ntchito mfundo ya kugawikana kwamagetsi kuti muchepetse voteji pachipata, MOSFET idzagwira ntchito bwino pamene magetsi olowera ali okwera kwambiri, koma mphamvu yolowera ikachepetsedwa, voteji yachipata imakhala yosakwanira, zomwe zimapangitsa kusakwanira conduction, potero kumawonjezera kugwiritsa ntchito mphamvu.

3. Kugwiritsa ntchito mphamvu ziwiri

M'mabwalo ena owongolera, gawo lamalingaliro limagwiritsa ntchito voteji ya digito ya 5V kapena 3.3V, pomwe gawo lamagetsi limagwiritsa ntchito voteji ya 12V kapena kupitilira apo. Ma voltages awiriwa amalumikizidwa ku malo amodzi.

Izi zimakweza kufunikira kogwiritsa ntchito dera kuti mbali yotsika-voltage imatha kuwongolera bwino MOSFET mbali yamagetsi apamwamba. Panthawi imodzimodziyo, MOSFET kumbali yamagetsi apamwamba idzakumananso ndi mavuto omwe atchulidwa mu 1 ndi 2.

Pamilandu itatu iyi, mawonekedwe a totem pole sangathe kukwaniritsa zofunikira, ndipo ma driver ambiri a MOSFET oyendetsa pashelufu sakuwoneka kuti akuphatikiza zipata zochepetsera magetsi.

 

Choncho ndinakonza dera loti ligwirizane ndi zosowa zitatuzi.

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Dalaivala wozungulira wa NMOS

Apa ndingopanga kusanthula kosavuta kwa dera la driver la NMOS:

Vl ndi Vh ndi magetsi otsika komanso apamwamba kwambiri. Ma voltages awiriwa akhoza kukhala ofanana, koma Vl sayenera kupitirira Vh.

Q1 ndi Q2 amapanga chipilala cha totem chopindika kuti akwaniritse kudzipatula ndikuwonetsetsa kuti machubu awiri oyendetsa Q3 ndi Q4 sayatsa nthawi imodzi.

R2 ndi R3 imapereka mafotokozedwe amagetsi a PWM. Posintha izi, dera limatha kuyendetsedwa pamalo pomwe mawonekedwe amtundu wa PWM ndi otsetsereka.

Q3 ndi Q4 amagwiritsidwa ntchito kupereka galimoto panopa. Ikayatsidwa, Q3 ndi Q4 zimangokhala ndi kutsika kocheperako kwa Vce poyerekeza ndi Vh ndi GND. Kutsika kwamagetsi kumeneku nthawi zambiri kumakhala pafupifupi 0.3V, komwe kumakhala kotsika kwambiri kuposa Vce ya 0.7V.

R5 ndi R6 ndi zotsutsana ndi mayankho, zomwe zimagwiritsidwa ntchito poyesa magetsi pachipata. Magetsi otsatiridwa amatulutsa malingaliro olakwika ku maziko a Q1 ndi Q2 kudzera pa Q5, motero amachepetsa mphamvu yamagetsi pachipata chochepa. Mtengo uwu ukhoza kusinthidwa kudzera pa R5 ndi R6.

Pomaliza, R1 imapereka malire apano a Q3 ndi Q4, ndipo R4 imapereka malire apano a MOSFET, omwe ndi malire a Ice wa Q3 ndi Q4. Ngati ndi kotheka, mathamangitsidwe capacitor akhoza chikugwirizana ndi R4.

Derali lili ndi izi:

1. Gwiritsani ntchito magetsi otsika ndi PWM kuyendetsa MOSFET yapamwamba.

2. Gwiritsani ntchito chizindikiro chaching'ono cha matalikidwe a PWM kuti muyendetse MOSFET yokhala ndi zofunikira zamagetsi apamwamba.

3. Malire apamwamba kwambiri a magetsi a pachipata

4. Kulowetsa ndi kutulutsa malire apano

5. Pogwiritsa ntchito zotsutsa zoyenera, mphamvu zochepa kwambiri zimatha kupindula.

6. Chizindikiro cha PWM chatembenuzidwa. NMOS sifunikira izi ndipo itha kuthetsedwa mwa kuyika inverter kutsogolo.

Popanga zida zonyamula ndi zopanda zingwe, kukonza magwiridwe antchito ndikukulitsa moyo wa batri ndi zinthu ziwiri zomwe opanga ayenera kukumana nazo. Ma converter a DC-DC ali ndi ubwino wogwiritsa ntchito bwino kwambiri, kutulutsa kwakukulu kwapano, komanso kutsika kocheperako komwe kumawapangitsa kukhala oyenera kugwiritsa ntchito zida zonyamulika. Pakalipano, zomwe zikuchitika pakukula kwa teknoloji ya DC-DC converter design ndi: (1) Ukadaulo wapamwamba kwambiri: Pamene kusintha kwafupipafupi kumawonjezeka, kukula kwa kusintha kosinthika kumachepetsedwanso, kachulukidwe ka mphamvu kumawonjezeka kwambiri, ndipo kuyankhidwa kwamphamvu kumakhala bwino. . Ma frequency osinthira amagetsi otsika a DC-DC amakwera mpaka pamlingo wa megahertz. (2) Ukadaulo wamagetsi otsika: Ndikukula kosalekeza kwaukadaulo wopanga ma semiconductor, mphamvu yogwiritsira ntchito ma microprocessors ndi zida zamagetsi zonyamula zikuyenda pang'onopang'ono, zomwe zimafuna osinthira amtsogolo a DC-DC kuti apereke magetsi otsika kuti agwirizane ndi ma microprocessors. zofunika kwa mapurosesa ndi kunyamula zipangizo zamagetsi.

Kukula kwa matekinolojewa kwapereka patsogolo zofunika zapamwamba pakupanga ma circuit chip magetsi. Choyamba, pamene kusintha kwafupipafupi kukukulirakulira, zofunikira zazikulu zimayikidwa pa ntchito ya kusintha zinthu. Nthawi yomweyo, ma switching element drive mabwalo ofananira amayenera kuperekedwa kuti awonetsetse kuti zinthu zosinthira zimagwira ntchito bwino pakusintha ma frequency mpaka MHz. Kachiwiri, pazida zamagetsi zoyendetsedwa ndi batri, mphamvu yogwira ntchito yozungulira ndi yotsika (mwachitsanzo, ma batri a lithiamu mwachitsanzo, voteji yogwira ntchito ndi 2.5 ~ 3.6V), motero, mphamvu yogwira ntchito ya chipangizo chamagetsi ndi yotsika.

 

MOSFET imakhala yotsika kwambiri yotsutsa ndipo imagwiritsa ntchito mphamvu zochepa. MOSFET nthawi zambiri imagwiritsidwa ntchito ngati chosinthira magetsi mu tchipisi todziwika bwino ta DC-DC. Komabe, chifukwa cha kuchuluka kwa ma parasitic capacitance a MOSFET, mphamvu yachipata cha machubu osinthira a NMOS nthawi zambiri imakhala yokwera mpaka makumi a picofarad. Izi zimayika patsogolo zofunikira pakupanga ma frequency apamwamba a DC-DC converter switching tube drive circuit.

M'mapangidwe otsika kwambiri a ULSI, pali mabwalo osiyanasiyana a CMOS ndi BiCMOS omwe amagwiritsa ntchito zida zolimbikitsira bootstrap ndikuyendetsa mabwalo ngati katundu wamkulu wa capacitive. Mabwalowa amatha kugwira ntchito bwino ndi magetsi otsika kuposa 1V, ndipo amatha kugwira ntchito pafupipafupi makumi a megahertz kapena mazana a megahertz okhala ndi mphamvu ya 1 mpaka 2pF. Nkhaniyi imagwiritsa ntchito kagawo kakang'ono ka bootstrap kuti ipange mayendedwe oyendetsa omwe ali ndi mphamvu yayikulu yoyendetsa galimoto yomwe ili yoyenera ma voliyumu otsika, osinthira ma frequency a DC-DC. Derali lidapangidwa kutengera njira ya Samsung AHP615 BiCMOS ndikutsimikiziridwa ndi kayesedwe ka Hspice. Pamene voteji kotunga ndi 1.5V ndi katundu capacitance ndi 60pF, pafupipafupi ntchito akhoza kufika kuposa 5MHz.

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Makhalidwe osintha a MOSFET

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1. Makhalidwe osasunthika

Monga chinthu chosinthira, MOSFET imagwiranso ntchito m'magawo awiri: kuzimitsa kapena kuyatsa. Popeza MOSFET ndi gawo loyendetsedwa ndi voteji, momwe ntchito yake imagwiritsidwira ntchito makamaka ndi magetsi a gate-source uGS.

 

Makhalidwe ogwira ntchito ndi awa:

※ uGS＜voltage UT: MOSFET imagwira ntchito pamalo odulidwa, iDS yapano ya drain-source ndi 0, voliyumu yotulutsa uDS≈UDD, ndipo MOSFET ili m'malo "ozimitsa".

※ uGS>Kuyatsa voteji UT: MOSFET imagwira ntchito m'dera la conduction, drain-source current iDS=UDD/(RD+rDS). Zina mwa izo, rDS ndi kukana-gwero la madzi pamene MOSFET yatsegulidwa. Mphamvu yotulutsa UDS=UDD?rDS/(RD+rDS), ngati rDS＜＜RD, uDS≈0V, MOSFET ili m'boma "pa".

2. Makhalidwe amphamvu

MOSFET imakhalanso ndi njira yosinthira pamene ikusintha pakati pa maiko ndi kuyatsa, koma mawonekedwe ake osinthika makamaka amadalira nthawi yomwe ikufunika kuti azilipiritsa ndi kutulutsa mphamvu yosokera yokhudzana ndi dera, komanso kusonkhanitsa ndi kutulutsa pamene chubu palokha chikuyatsidwa ndikuzimitsa. Nthawi yowonongeka ndi yochepa kwambiri.

Pamene magetsi olowetsa ui asintha kuchokera kumtunda kupita kumunsi ndipo MOSFET ikusintha kuchoka ku boma kupita ku boma, mphamvu ya UDD imayimitsa mphamvu yosokera CL kupyolera mu RD, ndi nthawi yolipiritsa nthawi zonse τ1=RDCL. Choncho, mphamvu yotulutsa uo imayenera kudutsa kuchedwa kwina musanasinthe kuchoka pa mlingo wotsika kupita kumtunda wapamwamba; pamene athandizira voteji ui asintha kuchokera kutsika kupita kumtunda ndipo MOSFET ikusintha kuchokera kumtunda kupita ku boma, mtengo wa CL wosokera umadutsa rDS Kutulutsa kumachitika ndi nthawi yotulutsa nthawi zonse τ2≈rDSCL. Zitha kuwoneka kuti mphamvu yotulutsa Uo ikufunikanso kuchedwa pang'ono isanasinthe kupita kumunsi. Koma chifukwa rDS ndi yaying'ono kwambiri kuposa RD, nthawi yotembenuka kuchoka pa odulidwa kupita ku conduction ndi yayifupi kuposa nthawi yotembenuka kuchoka pa conduction kupita ku kudula.

Popeza kukana kwa MOSFET kwa MOSFET kumakhala kokulirapo kuposa rCES ya transistor, komanso kukana kwakunja kwa RD kumakhalanso kwakukulu kuposa RC yotsutsa ya transistor, nthawi yolipira ndi kutulutsa. wa MOSFET ndi wautali, kupanga MOSFET Liwiro losinthira ndilotsika kuposa la transistor. Komabe, m'mabwalo a CMOS, popeza mabwalo othamangitsa ndi mabwalo othamangitsa onse ndi mabwalo ocheperako, njira zolipiritsa ndi zotulutsa zimakhala zachangu, zomwe zimapangitsa kuti ma CMOS azithamanga kwambiri.