MOSFET ulwazi olusisiseko kunye nokusetyenziswa

Ngokuphathelele kutheni indlela yokunciphisaIi-MOSFETsazisetyenziswanga, akukhuthazwa ukuba ufike ezantsi kwayo.

Kwezi MOSFET zimbini zophuculo, i-NMOS isetyenziswa kakhulu. Isizathu kukuba i-on-resistance incinci kwaye kulula ukuyenza. Ke ngoko, i-NMOS isetyenziswa ngokubanzi ekutshintsheni unikezelo lwamandla kunye nezicelo zokuqhuba iimoto. Kwintshayelelo elandelayo, i-NMOS isetyenziswa kakhulu.

Kukho amandla e-parasitic phakathi kwezikhonkwane ezintathu ze-MOSFET. Oku ayisiyiyo into esiyidingayo, kodwa ibangelwa yimida yenkqubo yokuvelisa. Ubukho be-parasitic capacitance yenza kube nzima ngakumbi xa uyila okanye ukhetha i-drive circuit, kodwa akukho ndlela yokuyiphepha. Siza kukwazisa ngokweenkcukacha kamva.

Kukho i-parasitic diode phakathi kombhobho kunye nomthombo. Oku kubizwa ngokuba yi-diode yomzimba. Le diode ibaluleke kakhulu xa uqhuba imithwalo ye-inductive (efana neenjini). Ngendlela, i-diode yomzimba ikhona kuphela kwi-MOSFET enye kwaye ayisoloko ifumaneka ngaphakathi kwe-chip yesekethe edibeneyo.

2. Iimpawu zokuqhuba ze-MOSFET

Ukuqhuba kuthetha ukusebenza njengotshintsho, olulingana nokuvalwa kokutshintsha.

Uphawu lwe-NMOS kukuba iya kuvulwa xa i-Vgs inkulu kunexabiso elithile. Kufanelekile ukusetyenziswa xa umthombo usekelwe (i-low-end drive), nje ukuba i-voltage yesango ifikelela kwi-4V okanye i-10V.

Iimpawu ze-PMOS kukuba iya kuvulwa xa i-Vgs ingaphantsi kwexabiso elithile, elifanelekileyo kwiimeko apho umthombo uxhunywe kwi-VCC (i-high-end drive). Nangona kunjalo, nangonaI-PMOSinokusetyenziswa ngokulula njengomqhubi ophezulu, i-NMOS idla ngokusetyenziswa kubaqhubi abaphezulu ngenxa yokumelana okukhulu, ixabiso eliphezulu, kunye neentlobo ezimbalwa zokutshintshwa.

3. MOS tshintsha ilahleko ityhubhu

Ingaba yi-NMOS okanye i-PMOS, kukho ukuxhathisa emva kokuba ivuliwe, ngoko ke okwangoku kuya kudla amandla kolu xhathiso. Le nxalenye yamandla asetyenzisiweyo ibizwa ngokuba yilahleko yokuqhuba. Ukukhetha i-MOSFET ene-on-resistance encinci kuya kunciphisa ilahleko yokuqhuba. Amandla asezantsi e-MOSFET ekumelaneni nokumelana ngokubanzi malunga namashumi eemiliyoni, kwaye kukho iimiliyoni ezininzi.

Xa i-MOSFET ivuliwe yaza yacinywa, mayingagqitywa ngoko nangoko. I-voltage kwi-MOS inenkqubo yokunciphisa, kwaye umsinga ohambayo unenkqubo ekhulayo. Ngeli xesha, iI-MOSFET'silahleko yimveliso yombane kunye neyangoku, ebizwa ngokuba yilahleko yokutshintsha. Ngokuqhelekileyo ukutshintsha ilahleko inkulu kakhulu kunelahleko yokuqhuba, kwaye ngokukhawuleza ukutshintshwa rhoqo, ilahleko inkulu.

Imveliso ye-voltage kunye neyangoku ngexesha lokuqhuba inkulu kakhulu, ibangela ilahleko enkulu. Ukunciphisa ixesha lokutshintsha kunokunciphisa ilahleko ngexesha lokuqhuba ngalunye; ukunciphisa i-frequency yokutshintsha kunokunciphisa inani lokutshintsha ngexesha leyunithi. Zombini iindlela zinokunciphisa ilahleko zokutshintsha.

Ukumaza xa i-MOSFET ilayitiwe. Ingabonwa ukuba imveliso ye-voltage kunye neyangoku ngexesha lokuqhuba inkulu kakhulu, kwaye ilahleko ebangelwayo nayo inkulu kakhulu. Ukunciphisa ixesha lokutshintsha kunokunciphisa ilahleko ngexesha lokuqhuba ngalunye; ukunciphisa i-frequency yokutshintsha kunokunciphisa inani lokutshintsha ngexesha leyunithi. Zombini iindlela zinokunciphisa ilahleko zokutshintsha.

4. Umqhubi we-MOSFET

Xa kuthelekiswa ne-bipolar transistors, kukholelwa ngokubanzi ukuba akukho okwangoku efunekayo ukuze uvule i-MOSFET, ukuba umbane we-GS uphezulu kunexabiso elithile. Oku kulula ukwenza, kodwa sikwafuna isantya.

Inokubonwa kwisakhiwo se-MOSFET ukuba kukho i-parasitic capacitance phakathi kwe-GS kunye ne-GD, kwaye ukuqhuba kwe-MOSFET ngokwenene kukuhlawula kunye nokukhutshwa kwe-capacitor. Ukutshaja i-capacitor kufuna i-current, kuba i-capacitor inokuthathwa njengesiphaluka esifutshane ngexesha lokutshaja, ngoko ke umbane okhawulezayo uya kuba mkhulu. Into yokuqala ekufuneka uyithathele ingqalelo xa ukhetha/uyila umqhubi we-MOSFET sisixa sesetyhula esifutshane sangoku esinokubonelela ngaso.

Into yesibini ekufuneka uyiqaphele kukuba i-NMOS, eqhele ukusetyenziselwa ukuqhuba okuphezulu, idinga umbane wesango ukuba ube mkhulu kunombane womthombo xa uvulwa. Xa i-MOSFET eqhutywa kwicala eliphezulu ivuliwe, amandla ombane omthombo ayafana ne-drain voltage (VCC), ngoko ke amandla ombane wesango yi-4V okanye i-10V enkulu kune-VCC ngeli xesha. Ukuba ufuna ukufumana i-voltage enkulu kuneVCC kwisistim enye, udinga isekethe ekhethekileyo yokunyusa. Abaqhubi beemoto abaninzi baneempompo ezidibeneyo zokuhlawula. Kufuneka kuqatshelwe ukuba i-capacitor yangaphandle efanelekileyo kufuneka ikhethwe ukufumana i-short-circuit current eyaneleyo ukuqhuba i-MOSFET.

I-4V okanye i-10V ekhankanywe ngasentla yi-voltage yokuvula yee-MOSFET ezisetyenziswa ngokuqhelekileyo, kwaye ngokuqinisekileyo umda othile kufuneka uvunyelwe ngexesha loyilo. Kwaye ukuphakama kwe-voltage, ngokukhawuleza isantya sokuqhuba kunye nokuncinci ukuchasana kokuqhuba. Ngoku kukho ii-MOSFETs ezinevoltheji ezincinci zokuqhuba ezisetyenziswa kwiindawo ezahlukeneyo, kodwa kwiisistim ze-12V zeemoto zemoto, ngokubanzi i-4V conduction yanele.

Kwisekethe yomqhubi we-MOSFET kunye neelahleko zayo, nceda ujonge kwiMicrochip's AN799 Matching MOSFET Drivers to MOSFETs. Ineenkcukacha kakhulu, ngoko ke andisayi kubhala ngaphezulu.

I-MOSFET luhlobo lweFET (enye yi-JFET). Ingenziwa kwimodi yokuphucula okanye imodi yokunciphisa, i-P-channel okanye i-N-channel, iindidi ezi-4 zizonke. Nangona kunjalo, kuphela imo yokuphucula i-N-channel MOSFET esetyenziswa ngokwenene. kunye nohlobo lophuculo lwe-P-channel MOSFET, ke i-NMOS okanye i-PMOS ihlala ibhekisa kwezi ntlobo zimbini.

5. Isekethe yesicelo seMOSFET?

Olona phawu lubalulekileyo lwe-MOSFET ziimpawu zayo ezilungileyo zokutshintsha, ke ngoko isetyenziswa kakhulu kwiisekethe ezifuna utshintsho lwe-elektroniki, njengokutshintsha izixhobo zombane kunye neemoto zokuqhuba, kunye nokukhanya kokukhanya.

Abaqhubi be-MOSFET banamhlanje banemfuno ezininzi ezizodwa:

1. Ukusetyenziswa kwamandla ombane aphantsi

Xa usebenzisa umbane we-5V, ukuba i-totem pole yendabuko isetyenziswe ngeli xesha, ekubeni i-transistor ibe ne-voltage drop malunga ne-0.7V, i-voltage yangempela yokugqibela esetyenziswe kwisango yi-4.3V kuphela. Ngeli xesha, sikhetha amandla esango eliqhelekileyo

Kukho umngcipheko othile xa usebenzisa i-4.5V MOSFET. Ingxaki efanayo iyenzeka xa usebenzisa i-3V okanye ezinye izixhobo zombane eziphantsi.

2. Ukusetyenziswa kombane obanzi

I-voltage yegalelo ayilona ixabiso elimiselweyo, liya kutshintsha kunye nexesha okanye ezinye izinto. Olu tshintsho lubangela ukuba amandla ombane okuqhuba abonelelwa yisekethe ye-PWM kwi-MOSFET angazinzi.

Ukuze kwenziwe ii-MOSFETs zikhuseleke phantsi kombane wesango eliphezulu, ii-MOSFET ezininzi zinezixhobo zokulawula amandla ombane ezakhelwe ngaphakathi ukuze zinciphise ngamandla amandla ombane wesango. Kule meko, xa umbane wokuqhuba obonelelweyo udlula umbane wetyhubhu yokulawula i-voltage, iya kubangela ukusetyenziswa kwamandla amakhulu.

Kwangaxeshanye, ukuba usebenzisa umgaqo wolwahlulo lombane we-resistor ukunciphisa i-voltage yesango, i-MOSFET iya kusebenza kakuhle xa i-voltage yegalelo iphezulu, kodwa xa igalelo lombane lincitshisiwe, i-voltage yesango iya kunganelanga, ibangele. ukuqhuba okungaphelelanga, ngaloo ndlela kunyuswa ukusetyenziswa kwamandla.

3. Ukusetyenziswa kwamandla amabini

Kwezinye iisekethe zolawulo, inxalenye ye-logic isebenzisa i-5V eqhelekileyo okanye i-3.3V yombane wedijithali, ngelixa inxalenye yamandla isebenzisa i-voltage ye-12V okanye nangaphezulu. Amandla ombane amabini aqhagamshelwe kumhlaba oqhelekileyo.

Oku kuphakamisa imfuneko yokusebenzisa isekethe ukwenzela ukuba icala le-low-voltage likwazi ukulawula ngokufanelekileyo i-MOSFET kwicala le-high-voltage. Kwangaxeshanye, i-MOSFET kwicala le-high-voltage iya kujongana neengxaki ezikhankanywe kwi-1 kunye ne-2.

Kwezi meko zintathu, ulwakhiwo lwepali yetotem alukwazi ukuhlangabezana neemfuno zemveliso, kwaye uninzi lwee-IC zomqhubi we-MOSFET ezingaphandle kweshelufa azibonakali zibandakanya izakhiwo zokunciphisa umbane wesango.

Ngoko ndayila isiphaluka esiqhelekileyo ukuze sihlangabezane nezi mfuno zintathu.

Isekethe yomqhubi we-NMOS

Apha ndiza kwenza uhlalutyo olulula lwesekethe yomqhubi we-NMOS:

I-Vl kunye ne-Vh zizixhobo zamandla ezisezantsi kunye neziphezulu ngokulandelelana. I-voltages ezimbini zinokufana, kodwa i-Vl akufanele idlule i-Vh.

I-Q1 kunye ne-Q2 zenza i-totem pole eguqulweyo ukuze ifikeleleke yodwa ngelixa iqinisekisa ukuba iibhubhu ezimbini zomqhubi i-Q3 kunye ne-Q4 azivuli ngexesha elifanayo.

I-R2 kunye ne-R3 zibonelela ngesalathiso sombane we-PWM. Ngokutshintsha le referensi, isekethe inokusebenza kwindawo apho i-wave wave ye-PWM ingumnqantsa.

I-Q3 kunye ne-Q4 zisetyenziselwa ukubonelela ngokuqhuba ngoku. Xa ivuliwe, i-Q3 kunye ne-Q4 ine-voltage encinci yokuhla kwe-Vce ngokumalunga ne-Vh kunye ne-GND. Oku kuhla kwamandla ombane kudla ngokuba malunga ne-0.3V kuphela, ephantsi kakhulu kune-Vce ye-0.7V.

I-R5 kunye ne-R6 zizixhasi zempendulo, ezisetyenziselwa ukwenza isampulu yombane wesango. I-voltage yesampuli ivelisa impendulo enamandla engalunganga kwiziseko ze-Q1 kunye ne-Q2 nge-Q5, ngaloo ndlela inciphisa i-voltage yesango kwixabiso elincinci. Eli xabiso lingahlengahlengiswa nge-R5 kunye ne-R6.

Ekugqibeleni, i-R1 ibonelela ngesiseko somda we-Q3 kunye ne-Q4, kwaye i-R4 inika umda wangoku wesango kwi-MOSFET, engumda we-Ice ye-Q3 kunye ne-Q4. Ukuba kuyimfuneko, i-acceleration capacitor inokudityaniswa ngokuhambelana ne-R4.

Le sekethi ibonelela ngezi mpawu zilandelayo:

1. Sebenzisa amandla ombane asezantsi kunye nePWM ukuqhuba iMOSFET kwicala eliphezulu.

2. Sebenzisa isignali ye-amplitude encinci ye-PWM ukuqhuba i-MOSFET ngeemfuno zombane wesango eliphezulu.

3. Incopho yomlinganiselo wombane wesango

4. Imida yangoku yokufaka kunye nemveliso

5. Ngokusebenzisa izichasi ezifanelekileyo, ukusetyenziswa kwamandla aphantsi kakhulu kunokufezekiswa.

6. Umqondiso wePWM ujikiwe. I-NMOS ayifuni eli nqaku kwaye inokusombulula ngokubeka inverter ngaphambili.

Xa uyila izixhobo eziphathwayo kunye neemveliso ezingenazingcingo, ukuphucula ukusebenza kwemveliso kunye nokwandisa ubomi bebhetri yimiba emibini abaqulunqi kufuneka bajongane nayo. Iziguquli ze-DC-DC zinenzuzo yokusebenza okuphezulu, imveliso enkulu yangoku, kunye ne-quiescent ephantsi yangoku, ibenza bafaneleke kakhulu ukunika amandla izixhobo eziphathwayo. Okwangoku, ezona ndlela ziphambili zophuhliso lwethekhnoloji yoyilo lwe-DC-DC yokuguqulela zezi: (1) Itekhnoloji ye-high-frequency: Njengoko i-frequency yokutshintsha inyuka, ubungakanani bomguquli wokutshintsha buye bancitshiswa, ubuninzi bamandla nabo banda kakhulu, kwaye impendulo eguquguqukayo iyaphuculwa. . I-frequency switching frequency ye-low-power converters DC-DC iya kunyuka ukuya kwinqanaba le-megahertz. (2) Itekhnoloji yamandla ombane asezantsi: Ngophuhliso oluqhubekayo lwetekhnoloji yokuvelisa i-semiconductor, amandla ombane osebenzayo we-microprocessors kunye nezixhobo zombane eziphathwayo ziya zisiba sezantsi naphantsi, nto leyo efuna abaguquli bexesha elizayo be-DC-DC ukuba babonelele ngemveliso yombane ephantsi ukuqhelanisa nee-microprocessors. iimfuno zeprosesa kunye nezixhobo zombane eziphathwayo.

Uphuhliso lobu bugcisa bubeke phambili iimfuno eziphezulu zoyilo lweesekethe zetshiphu zamandla. Okokuqala, njengoko i-frequency yokutshintsha iqhubeka nokunyuka, iimfuno eziphezulu zibekwe ekusebenzeni kwezinto zokutshintsha. Kwangaxeshanye, iisekethe ezihambelanayo zokutshintsha izinto zokuqhuba kufuneka zibonelelwe ukuze kuqinisekiswe ukuba izinto zokutshintsha zisebenza ngokuqhelekileyo ekutshintsheni i-frequencies ukuya kwi-MHz. Okwesibini, kwi-battery-powered portable electronic devices, i-voltage yokusebenza yesekethe iphantsi (ukuthatha iibhetri ze-lithium njengomzekelo, i-voltage esebenzayo yi-2.5 ~ 3.6V), ngoko ke, i-voltage esebenzayo ye-chip yamandla iphantsi.

I-MOSFET inoxhathiso oluphantsi kakhulu kwaye isebenzisa amandla aphantsi. I-MOSFET isoloko isetyenziswa njengotshintsho lwamandla kwiitshiphusi zeDC-DC ezidumileyo ngoku eziphezulu. Nangona kunjalo, ngenxa yomthamo omkhulu we-MOSFET we-parasitic, umthamo wesango leetyhubhu zokutshintsha ze-NMOS uphezulu ukuya kutsho kumashumi eepicofarads. Oku kubeka phambili iimfuno eziphezulu zoyilo lwezijikelezo zokusebenza eziphezulu ze-DC-DC zokuguqula i-tube drive circuit.

Kuyilo lwe-ULSI ene-voltage ephantsi, kukho iintlobo ngeentlobo zeesekethe ezinengqondo ze-CMOS kunye ne-BiCMOS zisebenzisa i-bootstrap boost structures kunye nokuqhuba iisekethe njengemithwalo emikhulu ye-capacitive. Ezi sekethe zinokusebenza ngokuqhelekileyo nge-voltage yobonelelo lwamandla engaphantsi kwe-1V, kwaye inokusebenza ngokuphindaphinda amashumi eemegahertz okanye namakhulu eemegahertz ezinomthamo womthwalo we-1 ukuya kwi-2pF. Eli nqaku lisebenzisa isekethe yokunyusa i-bootstrap ukuyila isekethe yokuqhuba enomthwalo omkhulu we-capacitance drive yesakhono esilungele umbane ophantsi, i-high switching frequency boost DC-DC converters. Isekethe yenzelwe ngokusekelwe kwinkqubo ye-Samsung AHP615 ye-BiCMOS kwaye iqinisekiswe yi-Hspice simulation. Xa i-voltage yokubonelela i-1.5V kunye ne-capacitance yomthwalo i-60pF, i-frequency yokusebenza inokufikelela ngaphezu kwe-5MHz.

Iimpawu zokutshintsha kwe-MOSFET

1. Iimpawu ezimileyo

Njengento yokutshintsha, i-MOSFET ikwasebenza kumazwe amabini: icinyiwe okanye ivuliwe. Ekubeni i-MOSFET ilicandelo elilawulwa ngamandla ombane, imeko yayo yokusebenza imiselwa ikakhulu yi-voltage yesango lomthombo we-uGS.

Iimpawu zokusebenza zezi zilandelayo:

※ uGS＜i-voltage yokuvula i-UT: I-MOSFET isebenza kwindawo esikiweyo, i-iDS yangoku ye-drain-source ngoku ngu-0, i-voltage ephumayo i-uDS≈UDD, kwaye i-MOSFET ikwimo "yokucima".

※ uGS>Vula amandla ombane e-UT: I-MOSFET isebenza kwindawo yokuqhuba, i-drain-source yangoku iDS=UDD/(RD+rDS). Phakathi kwazo, i-rDS luxhathiso lwemithombo yotsalo-manzi xa i-MOSFET ivuliwe. Amandla ombane wemveliso UDS=UDD?rDS/(RD+rDS), ukuba i-rDS＜＜RD, uDS≈0V, iMOSFET ikwimo "ivuliwe".

2. Iimpawu ezinamandla

I-MOSFET ikwanayo nenkqubo yotshintsho xa utshintsha phakathi kwamazwe, kodwa iimpawu zayo eziguquguqukayo zixhomekeke ikakhulu kwixesha elifunekayo lokuhlawulisa kunye nokukhupha amandla alahlekileyo anxulumene nesekethe, kunye nokuqokelelwa kwentlawulo kunye nokukhutshwa xa ityhubhu ngokwayo ivuliwe kwaye ivaliwe. Ixesha lokuphumla lincinci kakhulu.

Xa amandla ombane we-ui etshintsha ukusuka phezulu ukuya ezantsi kwaye iMOSFET itshintsha ukusuka kwimeko ukuya kwimeko ecinyiweyo, unikezelo lwamandla lwe-UDD luhlawulisa amandla alahlekileyo CL nge-RD, kunye nexesha lokutshaja rhoqo τ1=RDCL. Ngoko ke, i-voltage ye-output uo idinga ukuhamba ngokulibaziseka okuthile ngaphambi kokutshintsha ukusuka kwinqanaba eliphantsi ukuya kwinqanaba eliphezulu; xa igalelo lombane we-ui utshintsha ukusuka ezantsi ukuya phezulu kwaye i-MOSFET itshintsha ukusuka kwi-off state ukuya kwimeko, intlawulo kwi-Lay capacitance CL idlula kwi-rDS Ukukhutshwa kwenzeka ngexesha lokukhupha rhoqo τ2≈rDSCL. Ingabonwa ukuba i-voltage ephumayo i-Uo ifuna ukulibaziseka okuthile ngaphambi kokuba itshintshele kwinqanaba eliphantsi. Kodwa ngenxa yokuba i-rDS incinci kakhulu kune-RD, ixesha lokuguqulwa ukusuka kwi-cut-off ukuya kwi-conduction lifutshane kunexesha lokuguqulwa ukusuka ekuqhubeni ukuya kwi-cut-cut.

Ekubeni i-drain-source resistance rDS ye-MOSFET xa ivuliwe inkulu kakhulu kune-saturation resistance rCES ye-transistor, kunye ne-RD yokumelana ne-drain yangaphandle inkulu kune-RC yokumelana nomqokeleli we-transistor, ixesha lokutshaja kunye nokukhupha. ye-MOSFET inde, yenza i-MOSFET Isantya sokutshintsha sisezantsi kuneso se-transistor. Nangona kunjalo, kwiisekethe ze-CMOS, kuba isekethe yokutshaja kunye nesekethe yokukhupha zombini zizijikelezo ezixhathisayo, iinkqubo zokutshaja kunye nokukhupha zikhawuleza, okukhokelela kwisantya esiphezulu sokutshintsha kwisekethe yeCMOS.