Babban Kunshin MOSFET Da'irar Direba

Da farko dai, nau'in MOSFET da tsari,MOSFETFET ne (wani JFET), ana iya ƙera shi zuwa nau'in haɓakawa ko raguwa, P-channel ko tashar N-tashar duka nau'ikan nau'ikan guda huɗu ne, amma ainihin aikace-aikacen MOSFET na N-channel kawai ingantacce da ingantaccen tashar P-tashar MOSFET, don haka yawanci ana kiransa NMOS ko PMOS yana nufin waɗannan nau'ikan guda biyu. Ga waɗannan nau'ikan MOSFET guda biyu waɗanda aka haɓaka, mafi yawan amfani da su shine NMOS, dalilin shine akan juriya kaɗan ne, kuma mai sauƙin ƙira. Don haka, ana amfani da NMOS gabaɗaya wajen sauya wutar lantarki da aikace-aikacen tuƙi.

A cikin gabatarwa mai zuwa, yawancin shari'o'in NMOS ne ke mamaye su. karfin ikon parasitic yana wanzuwa tsakanin fil uku na MOSFET, fasalin da ba a buƙata amma ya taso saboda iyakokin tsarin masana'antu. Kasancewar ƙarfin ƙarfin parasitic yana sa ya zama ɗan wahala don ƙira ko zabar da'irar direba. Akwai diode parasitic tsakanin magudanar ruwa da tushen. Wannan shi ake kira da body diode kuma yana da mahimmanci wajen tuki lodin inductive kamar injina. Af, diode jiki yana samuwa ne kawai a cikin MOSFET guda ɗaya kuma yawanci baya kasancewa a cikin guntu IC.

MOSFETsauya asarar bututu, ko NMOS ne ko PMOS, bayan gudanar da juriya ya wanzu, ta yadda na yanzu zai cinye makamashi a cikin wannan juriya, wannan ɓangaren makamashin da ake amfani da shi ana kiransa hasara. Zaɓin MOSFETs tare da ƙarancin juriya zai rage asarar juriya. A zamanin yau, akan juriya na MOSFETs masu ƙarancin ƙarfi gabaɗaya yana kusa da dubun milliohms, kuma ana samun ƴan milliohms kaɗan. Dole ne MOSFETs ba za a kammala su nan take ba lokacin da suke kunnawa da kashewa. Akwai tsarin rage ƙarfin wutar lantarki a Ƙarshen biyu na MOSFET, kuma akwai wani tsari na ƙara yawan wutar lantarki da ke gudana a cikinsa. A cikin wannan lokacin, asarar MOSFET shine samfurin lantarki da kuma ƙaddamarwa. halin yanzu, wanda ake kira hasara mai canzawa. Yawanci asarar sauyawa ya fi girma fiye da asarar gudanarwa, kuma da sauri saurin sauyawa, mafi girma asarar. Samfurin ƙarfin lantarki da na yanzu a lokacin da ake sarrafawa yana da girma sosai, yana haifar da asara mai yawa. Rage lokacin sauyawa yana rage asarar a kowace gudanarwa; rage mitar sauyawa yana rage adadin masu sauyawa kowane lokaci naúrar. Duk waɗannan hanyoyin suna rage asarar canzawa.

Idan aka kwatanta da transistors na bipolar, gabaɗaya an yarda cewa babu wani halin yanzu da ake buƙatar yin aMOSFETgudanar, muddin GS ƙarfin lantarki yana sama da wani ƙima. Wannan yana da sauƙin yin, duk da haka, muna kuma buƙatar gudu. Kamar yadda kuke gani a cikin tsarin MOSFET, akwai ƙarfin ƙarfin parasitic tsakanin GS, GD, kuma tuƙin MOSFET shine, a zahiri, caji da fitarwa na capacitance. Yin cajin capacitor yana buƙatar halin yanzu, saboda cajin capacitor nan take ana iya ganin shi a matsayin ɗan gajeren kewayawa, don haka ƙarfin halin yanzu zai kasance mafi girma. Abu na farko da za a lura lokacin zabar / zana direban MOSFET shine girman gajeriyar da'irar halin yanzu wanda za'a iya bayarwa.

Abu na biyu da za a lura shi ne cewa, gabaɗaya ana amfani da su a cikin babban tuƙi na NMOS, ƙarfin wutar lantarki na ƙofar kan lokaci yana buƙatar girma fiye da ƙarfin tushen tushen. MOSFET mai ƙarfi mai ƙarfi akan wutar lantarki ta tushen da ƙarfin magudanar ruwa (VCC) iri ɗaya, don haka wutar lantarki ta ƙofar fiye da VCC 4V ko 10V. idan a cikin tsarin guda ɗaya, don samun ƙarfin lantarki mafi girma fiye da VCC, muna buƙatar ƙwarewa a cikin haɓaka haɓakawa. Yawancin direbobin motoci sun haɗa famfunan caji, yana da mahimmanci a lura cewa yakamata ku zaɓi ƙarfin waje da ya dace don samun isassun gajeriyar kewayawa don fitar da MOSFET. 4V ko 10V shine MOSFET da aka saba amfani da shi akan ƙarfin lantarki, ƙirar ba shakka, kuna buƙatar samun takamaiman gefe. Mafi girman ƙarfin wutar lantarki, saurin kan-jihar gudun kuma ƙananan juriya na kan-jihar. Yanzu akwai kuma ƙananan wutar lantarki MOSFETs da ake amfani da su a fannoni daban-daban, amma a cikin tsarin lantarki na motoci na 12V, gabaɗaya 4V a kan-jihar ya isa.MOSFETs mafi mahimmancin fasalin shine halayen canzawa na mai kyau, don haka ana amfani dashi sosai a cikin bukatu na da'irori masu sauyawa na lantarki, kamar sauya wutar lantarki da tukin mota, amma har da hasken wuta. Gudanarwa yana nufin yin aiki azaman mai canzawa, wanda yayi daidai da rufewar sauyawa.Halayen NMOS, Vgs mafi girma fiye da wani ƙima za su gudanar, dacewa don amfani a cikin yanayin lokacin da tushen ya kasance ƙasa (ƙananan motsi), muddin ƙofar. Wutar lantarki na 4V ko 10V.PMOS halaye, Vgs kasa da wani ƙima zai gudanar, dace da amfani a cikin yanayin lokacin da aka haɗa tushen zuwa VCC (high-end drive). Koyaya, kodayake ana iya amfani da PMOS cikin sauƙin azaman babban direba na ƙarshe, NMOS galibi ana amfani dashi a cikin manyan direbobi saboda babban juriya, farashi mai girma, da nau'ikan maye gurbin.

Yanzu MOSFET yana fitar da aikace-aikacen ƙarancin wutar lantarki, lokacin amfani da wutar lantarki na 5V, wannan lokacin idan kun yi amfani da tsarin igiya na gargajiya na totem, saboda transistor ya kasance kusan 0.7V ƙarfin lantarki, wanda ya haifar da ainihin ƙarshe da aka ƙara zuwa ƙofar akan Wutar lantarki shine kawai 4.3 V. A wannan lokacin, zamu zaɓi ƙarancin ƙarfin ƙofa na 4.5V na MOSFET akan kasancewar wasu haɗari. Irin wannan matsala tana faruwa a cikin amfani da 3V ko wasu lokuta masu ƙarancin wutar lantarki. Ana amfani da wutar lantarki mai dual a wasu da'irori masu sarrafawa inda sashin dabaru yana amfani da irin ƙarfin lantarki na dijital 5V ko 3.3V kuma sashin wutar lantarki yana amfani da 12V ko ma mafi girma. Ana haɗa wutar lantarki guda biyu ta amfani da ƙasa ɗaya. Wannan yana sanya buƙatu don amfani da kewayawa wanda ke ba da damar ƙaramin ƙarfin lantarki don sarrafa MOSFET yadda ya kamata a kan babban ƙarfin wutar lantarki, yayin da MOSFET a gefen babban ƙarfin wutar lantarki zai fuskanci irin waɗannan matsalolin da aka ambata a cikin 1 da 2. A cikin dukkan lokuta uku, Tsarin sandar sandar totem ba zai iya biyan buƙatun fitarwa ba, kuma yawancin direbobin MOSFET ICs ba su haɗa da tsarin iyakance wutar lantarki ba. Wutar shigar da wutar lantarki ba ƙayyadadden ƙima ba ne, yana bambanta da lokaci ko wasu dalilai. Wannan bambancin yana haifar da wutar lantarki da aka bayar ga MOSFET ta da'irar PWM ya zama mara ƙarfi. Domin tabbatar da MOSFET daga manyan wutar lantarki na kofa, MOSFET da yawa suna da ginanniyar sarrafa wutar lantarki don iyakance girman ƙarfin wutar lantarki da ƙarfi.

A wannan yanayin, lokacin da ƙarfin wutar lantarki da aka bayar ya wuce ƙarfin lantarki na mai sarrafawa, zai haifar da babban amfani da wutar lantarki A lokaci guda, idan kawai kuna amfani da ka'idar mai rarraba wutar lantarki don rage ƙarfin ƙofar, za a sami ɗan ƙaramin ƙarfi. babban ƙarfin shigar da wutar lantarki, MOSFET yana aiki da kyau, yayin da ƙarfin shigarwar yana raguwa lokacin da ƙarfin wutar lantarki bai isa ya haifar da ƙarancin isasshiyar wutar lantarki ba, don haka ƙara yawan wutar lantarki.

Dangantakar da'irar gama gari anan kawai don da'irar direban NMOS don yin bincike mai sauƙi: Vl da Vh sune ƙarancin ƙarancin ƙarfi da ƙarfin wutar lantarki, bi da bi, ƙarfin lantarki biyu na iya zama iri ɗaya, amma Vl kada ya wuce Vh. Q1 da Q2 sun samar da sandar totem da aka juyar da su, ana amfani da su don cimma warewa, kuma a lokaci guda don tabbatar da cewa bututun direba biyu Q3 da Q4 ba za su kasance a lokaci guda ba. R2 da R3 suna ba da ma'anar wutar lantarki ta PWM, kuma ta hanyar canza wannan tunani, za ku iya yin aikin kewayawa da kyau, kuma ƙarfin wutar lantarki bai isa ya haifar da cikakkiyar gudanarwa ba, don haka ƙara yawan wutar lantarki. R2 da R3 suna ba da ma'anar wutar lantarki ta PWM, ta hanyar canza wannan tunani, zaku iya barin aikin kewayawa a cikin siginar siginar PWM yana da ɗan tsayi kuma madaidaiciya. Ana amfani da Q3 da Q4 don samar da halin yanzu, saboda kan lokaci, Q3 da Q4 dangane da Vh da GND sune mafi ƙarancin raguwar wutar lantarki na Vce, wannan raguwar ƙarfin lantarki yawanci 0.3V ne ko makamancin haka, ƙasa da ƙasa. fiye da 0.7V Vce R5 da R6 sune masu jujjuya ra'ayi don samfurin ƙarfin lantarki na ƙofar, bayan an gwada ƙarfin lantarki, ana amfani da wutar lantarki ta ƙofar azaman abin amsawa ga wutar lantarki, da ƙarfin lantarki na gate. ana amfani da samfurin zuwa wutar lantarki. R5 da R6 sune resistors na amsawa da ake amfani da su don samfurin ƙarfin lantarki na ƙofar, wanda daga nan aka wuce ta Q5 don ƙirƙirar ra'ayi mara kyau akan tushe na Q1 da Q2, don haka yana iyakance wutar lantarkin ƙofar zuwa ƙimar iyaka. Ana iya daidaita wannan ƙimar ta R5 da R6. A ƙarshe, R1 yana ba da ƙayyadaddun ƙayyadaddun tushe na yanzu zuwa Q3 da Q4, kuma R4 yana ba da iyakancewar ƙofar halin yanzu zuwa MOSFETs, wanda shine iyakancewar Ice na Q3Q4. Ana iya haɗa capacitor na hanzari a layi daya sama da R4 idan ya cancanta.                                         

Lokacin zayyana na'urori masu ɗaukuwa da samfuran mara waya, haɓaka aikin samfur da tsawaita lokacin aiki baturi abubuwa biyu ne da masu zanen kaya ke buƙatar fuskantar.DC-DC masu juyawa suna da fa'idodin babban inganci, babban fitarwa na halin yanzu da ƙarancin ƙarancin halin yanzu, waɗanda suka dace sosai don ƙarfafa šaukuwa. na'urori.

Masu juyawa na DC-DC suna da fa'idodi na babban inganci, babban fitarwa na halin yanzu da ƙarancin halin yanzu, waɗanda suka dace sosai don kunna na'urori masu ɗaukuwa. A halin yanzu, manyan abubuwan da ke faruwa a ci gaban fasahar ƙira ta DC-DC sun haɗa da: fasaha mai saurin gaske: tare da haɓaka mitar sauyawa, girman mai canzawa kuma yana raguwa, ƙarfin wutar lantarki ya ƙaru sosai, da kuzari mai ƙarfi. An inganta martani. Karami

Powerarfin DC-DC mai sauyawa mitar zai tashi zuwa matakin megahertz. Low fitarwa ƙarfin lantarki fasaha: Tare da ci gaba da ci gaban semiconductor masana'antu fasahar, microprocessors da šaukuwa lantarki kayan aiki ƙarfin lantarki aiki da ƙarfin lantarki yana samun ƙasa da ƙasa, wanda na bukatar nan gaba DC-DC Converter iya samar da low fitarwa ƙarfin lantarki don daidaita da microprocessor da šaukuwa lantarki kayan aiki, wanda. yana buƙatar mai canza DC-DC na gaba zai iya samar da ƙananan ƙarfin fitarwa don dacewa da microprocessor.

Isasshen samar da ƙananan ƙarfin fitarwa don daidaitawa zuwa microprocessors da kayan lantarki masu ɗaukuwa. Waɗannan ci gaban fasaha sun gabatar da buƙatu mafi girma don ƙirar ƙirar guntun wutar lantarki. Da farko, tare da ƙara yawan sauyawar sauyawa, ana sanya aikin abubuwan da aka gyara a gaba

Babban buƙatun don aiwatar da abubuwan canzawa, kuma dole ne su kasance suna da madaidaicin madaidaicin madaidaicin madauri don tabbatar da cewa abin canzawa a cikin mitar sauyawa har zuwa matakin megahertz na aiki na yau da kullun. Na biyu, na na'urorin lantarki masu ɗaukuwa masu amfani da baturi, ƙarfin wutar lantarkin da'irar ba ta da ƙarfi (a yanayin baturan lithium, alal misali).

Batirin lithium, alal misali, ƙarfin aiki na 2.5 ~ 3.6V), don haka guntuwar wutar lantarki don ƙananan ƙarfin lantarki.

MOSFET yana da ƙarancin juriya, ƙarancin amfani da kuzari, a cikin mashahurin babban guntu na DC-DC mafi inganci na yanzu ƙarin MOSFET azaman canjin wuta. Duk da haka, saboda babban ƙarfin ikon MOSFETs. Wannan yana sanya buƙatu mafi girma akan ƙira na canza da'irar direban bututu don zayyana babban mitar DC-DC masu juyawa. Akwai nau'ikan CMOS daban-daban, da'irori dabaru na BiCMOS ta amfani da tsarin haɓaka bootstrap da da'irori na direba azaman manyan kayan aiki masu ƙarfi a cikin ƙirar ULSI mai ƙarancin wuta. Wadannan da'irori suna iya yin aiki da kyau a ƙarƙashin yanayin ƙarancin wutar lantarki na ƙasa da 1V, kuma suna iya aiki a ƙarƙashin yanayin ƙarfin ɗaukar nauyi 1 ~ 2pF mitar na iya kaiwa dubun megabits ko ma ɗaruruwan megahertz. A cikin wannan takarda, ana amfani da da'irar haɓaka haɓakar bootstrap don ƙira babban ƙarfin ƙarfin ɗaukar nauyi, wanda ya dace da ƙarancin wutar lantarki, haɓaka mitar mitar mai haɓaka DC-DC mai juyawa. Ƙarshen wutar lantarki da PWM don fitar da MOSFET masu girma. ƙaramin siginar PWM mai ƙarfi don fitar da buƙatun ƙarfin wutar lantarki na MOSFETs.