Yog vim li cas depletion homMOSFETstsis siv, nws tsis pom zoo kom tau mus rau hauv qab ntawm nws.
Rau ob qho kev txhim kho-mos MOSFETs, NMOS feem ntau siv. Yog vim li cas yog tias qhov kev tiv thaiv yog me me thiab yooj yim rau kev tsim khoom. Yog li ntawd, NMOS feem ntau yog siv los hloov cov khoom siv hluav taws xob thiab kev siv lub cev muaj zog. Hauv cov lus qhia hauv qab no, NMOS feem ntau yog siv.
Muaj cov kab mob parasitic ntawm peb tus pins ntawm MOSFET. Qhov no tsis yog qhov peb xav tau, tab sis yog tshwm sim los ntawm kev tsim cov txheej txheem txwv. Lub hav zoov ntawm parasitic capacitance ua rau nws muaj teeb meem ntau dua thaum tsim lossis xaiv ib lub voj voog tsav, tab sis tsis muaj txoj hauv kev los zam nws. Peb yuav qhia nws kom meej tom qab.
Muaj cov kab mob parasitic ntawm qhov ntws thiab qhov chaw. Qhov no yog hu ua lub cev diode. Qhov no diode tseem ceeb heev thaum tsav tsheb inductive loads (xws li motors). Los ntawm txoj kev, lub cev diode tsuas muaj nyob rau hauv ib qho MOSFET nkaus xwb thiab feem ntau tsis pom nyob rau hauv ib qho kev sib xyaw ua ke nti.
2. MOSFET conduction yam ntxwv
Kev coj ua txhais tau tias ua raws li kev hloov pauv, uas sib npaug rau qhov hloov tau kaw.
Tus yam ntxwv ntawm NMOS yog tias nws yuav qhib thaum Vgs ntau dua li tus nqi. Nws yog tsim rau siv thaum lub hauv paus yog grounded (tsawg-kawg tsav), tsuav yog lub rooj vag voltage mus txog 4V los yog 10V.
Cov yam ntxwv ntawm PMOS yog tias nws yuav tig rau thaum Vgs tsawg dua li qee tus nqi, uas yog tsim rau cov xwm txheej uas qhov chaw txuas nrog VCC (high-end drive). Txawm li cas los xij, txawm tiasPMOStuaj yeem siv tau yooj yim ua tus tsav tsheb siab, NMOS feem ntau yog siv rau cov tsav tsheb siab kawg vim muaj kev tiv thaiv loj, tus nqi siab, thiab ob peb hom hloov.
3. MOS hloov raj poob
Txawm hais tias nws yog NMOS lossis PMOS, muaj kev tawm tsam tom qab nws qhib, yog li tam sim no yuav siv lub zog ntawm qhov kev tawm tsam no. Qhov no ntawm lub zog noj yog hu ua conduction poob. Xaiv ib tug MOSFET nrog ib tug me me ntawm-tiv taus yuav txo tau conduction poob. Niaj hnub no lub zog qis MOSFET ntawm kev ua haujlwm feem ntau yog nyob ib ncig ntawm kaum ntawm milliohms, thiab kuj tseem muaj ob peb milliohms.
Thaum MOSFET qhib thiab tawm, nws yuav tsum tsis txhob ua kom tiav tam sim ntawd. Qhov hluav taws xob thoob plaws MOS muaj cov txheej txheem txo qis, thiab cov dej ntws tam sim no muaj cov txheej txheem nce ntxiv. Thaum lub sij hawm no, lubMOSFET'spoob yog cov khoom ntawm voltage thiab tam sim no, uas yog hu ua switching poob. Feem ntau hloov pauv qhov poob yog qhov loj dua qhov kev poob qis, thiab qhov nrawm dua qhov hloov pauv, qhov poob ntau dua.
Cov khoom ntawm qhov voltage thiab tam sim no ntawm conduction yog loj heev, ua rau poob zoo heev. Txo lub sijhawm hloov pauv tuaj yeem txo qhov poob thaum txhua qhov kev coj ua; txo qhov hloov zaus tuaj yeem txo tus naj npawb ntawm cov keyboards ib lub sijhawm. Ob txoj kev tuaj yeem txo qhov kev poob qis.
Lub waveform thaum lub MOSFET qhib. Nws tuaj yeem pom tau tias cov khoom ntawm qhov hluav taws xob thiab qhov tam sim no ntawm kev ua haujlwm yog qhov loj heev, thiab qhov poob tshwm sim kuj loj heev. Txo lub sijhawm hloov pauv tuaj yeem txo qhov poob thaum txhua qhov kev coj ua; txo qhov hloov zaus tuaj yeem txo tus naj npawb ntawm cov keyboards ib lub sijhawm. Ob txoj kev tuaj yeem txo qhov kev poob qis.
4. MOSFET tsav tsheb
Piv nrog rau bipolar transistors, feem ntau ntseeg tau tias tsis muaj tam sim no yuav tsum tau tig rau MOSFET, tsuav yog qhov GS voltage siab dua ib qho nqi. Qhov no yooj yim ua, tab sis peb kuj xav tau ceev.
Nws tuaj yeem pom nyob rau hauv cov qauv ntawm MOSFET tias muaj cov kab mob parasitic capacitance ntawm GS thiab GD, thiab kev tsav tsheb ntawm MOSFET yog qhov tseeb ntawm tus nqi thiab tawm ntawm lub capacitor. Them lub capacitor yuav tsum muaj tam sim no, vim hais tias lub capacitor tuaj yeem suav tias yog luv luv ntawm lub sijhawm them, yog li tam sim no tam sim no yuav loj heev. Thawj qhov uas yuav tsum tau them sai sai rau thaum xaiv / tsim tus tsav tsheb MOSFET yog tus nqi tam sim no luv luv tam sim no nws tuaj yeem muab tau. cov
Qhov thib ob uas yuav tsum nco ntsoov yog tias NMOS, uas feem ntau siv rau kev tsav tsheb siab, xav tau lub rooj vag hluav taws xob kom siab dua qhov hluav taws xob thaum qhib. Thaum lub high-sided tsav MOSFET yog qhib, qhov voltage yog tib yam li qhov ntws voltage (VCC), yog li lub rooj vag voltage yog 4V lossis 10V ntau dua VCC lub sijhawm no. Yog tias koj xav kom tau txais qhov hluav taws xob loj dua VCC hauv tib lub cev, koj xav tau lub zog tshwj xeeb. Muaj ntau lub cev muaj zog tsav tsheb muaj cov twj tso kua mis. Nws yuav tsum raug sau tseg tias qhov tsim nyog sab nraud capacitor yuav tsum raug xaiv kom tau txais qhov luv luv tam sim no los tsav MOSFET.
Lub 4V lossis 10V tau hais los saum toj no yog qhov hloov pauv ntawm cov MOSFET uas nquag siv, thiab tau kawg muaj qee qhov npoo yuav tsum tau tso cai thaum tsim. Thiab qhov siab dua qhov voltage, qhov ceev ntawm conduction ceev thiab qhov me me ntawm conduction kuj. Tam sim no muaj MOSFETs nrog me me conduction voltages siv nyob rau hauv txawv teb, tab sis nyob rau hauv 12V automotive electronic systems, feem ntau 4V conduction yog txaus.
Rau MOSFET tsav tsheb Circuit Court thiab nws qhov poob, thov xa mus rau Microchip's AN799 Matching MOSFET Drivers rau MOSFETs. Nws yog cov ncauj lus kom ntxaws heev, yog li kuv yuav tsis sau ntxiv.
Cov khoom ntawm qhov voltage thiab tam sim no ntawm conduction yog loj heev, ua rau poob zoo heev. Txo lub sijhawm hloov pauv tuaj yeem txo qhov poob thaum txhua qhov kev coj ua; txo qhov hloov zaus tuaj yeem txo tus naj npawb ntawm cov keyboards ib lub sijhawm. Ob txoj kev tuaj yeem txo qhov kev poob qis.
MOSFET yog hom FET (lwm yam yog JFET). Nws tuaj yeem ua rau hauv hom kev txhim kho lossis depletion hom, P-channel lossis N-channel, tag nrho ntawm 4 hom. Txawm li cas los xij, tsuas yog kev txhim kho-hom N-channel MOSFET tau siv tiag tiag. thiab txhim kho-hom P-channel MOSFET, yog li NMOS lossis PMOS feem ntau xa mus rau ob hom no.
5. MOSFET daim ntawv thov Circuit Court?
Cov yam ntxwv tseem ceeb tshaj plaws ntawm MOSFET yog nws qhov kev hloov pauv zoo, yog li nws tau siv dav hauv cov khoom siv hluav taws xob uas xav tau hluav taws xob hloov hluav taws xob, xws li hloov cov khoom siv hluav taws xob thiab lub cev muaj zog, nrog rau cov teeb pom kev zoo.
Niaj hnub no cov neeg tsav tsheb MOSFET muaj ntau yam tshwj xeeb:
1. Kev siv hluav taws xob tsawg
Thaum siv 5V fais fab mov, yog siv cov qauv totem ib txwm siv nyob rau lub sijhawm no, txij li lub transistor yuav tsum muaj qhov hluav taws xob poob li ntawm 0.7V, qhov kawg qhov hluav taws xob siv rau lub rooj vag tsuas yog 4.3V. Lub sijhawm no, peb xaiv lub rooj vag nominal zog
Muaj qee qhov kev pheej hmoo thaum siv 4.5V MOSFET. Tib qhov teeb meem kuj tshwm sim thaum siv 3V lossis lwm yam khoom siv hluav taws xob qis.
2. Daim ntawv thov dav voltage
Lub input voltage tsis yog tus nqi ruaj khov, nws yuav hloov nrog lub sijhawm lossis lwm yam. Qhov kev hloov no ua rau lub zog tsav tsheb los ntawm PWM Circuit Court rau MOSFET tsis ruaj khov.
Yuav kom MOSFETs muaj kev nyab xeeb nyob rau hauv lub rooj vag siab voltages, ntau MOSFETs muaj built-in voltage regulators rau forcefully txwv lub amplitude ntawm lub rooj vag voltage. Nyob rau hauv cov ntaub ntawv no, thaum muab tsav voltage tshaj qhov voltage ntawm lub voltage regulator raj, nws yuav ua rau loj static zog noj.
Nyob rau tib lub sijhawm, yog tias koj tsuas yog siv lub hauv paus ntsiab lus ntawm kev faib hluav taws xob tiv thaiv kom txo tau lub rooj vag voltage, MOSFET yuav ua haujlwm zoo thaum lub input voltage kuj siab, tab sis thaum lub input voltage txo, lub rooj vag voltage yuav tsis txaus, ua rau. tsis tiav conduction, yog li nce zog noj.
3. Dual voltage daim ntawv thov
Hauv qee qhov kev tswj xyuas, lub logic feem siv 5V lossis 3.3V digital voltage, thaum lub zog siv hluav taws xob ntawm 12V lossis siab dua. Ob qhov hluav taws xob txuas mus rau ib qho av sib xws.
Qhov no nce qhov yuav tsum tau siv lub voj voog kom cov sab qis-voltage tuaj yeem tswj tau MOSFET ntawm sab high-voltage. Nyob rau tib lub sijhawm, MOSFET ntawm sab high-voltage kuj tseem yuav ntsib cov teeb meem hais hauv 1 thiab 2.
Hauv peb qhov xwm txheej no, tus qauv totem ncej tsis tuaj yeem ua tau raws li qhov yuav tsum tau ua, thiab ntau qhov chaw tawm ntawm MOSFET tsav tsheb ICs tsis zoo li suav nrog lub rooj vag voltage txwv cov qauv.
Yog li kuv tsim ib lub voj voog dav dav kom tau raws li peb qhov kev xav tau no.
cov
Tsav Circuit Court rau NMOS
Ntawm no kuv tsuas yog ua ib qho yooj yim tsom xam ntawm NMOS tsav tsheb Circuit Court:
Vl thiab Vh yog cov khoom siv hluav taws xob qis thiab siab kawg. Ob qhov hluav taws xob tuaj yeem ua tau zoo ib yam, tab sis Vl yuav tsum tsis pub tshaj Vh.
Q1 thiab Q2 tsim ib qho inverted totem ncej kom ua tiav kev sib cais thaum xyuas kom meej tias ob lub raj tsav tsheb Q3 thiab Q4 tsis tig rau tib lub sijhawm.
R2 thiab R3 muab PWM voltage siv. Los ntawm kev hloov qhov kev siv no, lub voj voog tuaj yeem ua haujlwm nyob rau hauv txoj haujlwm uas PWM teeb liab waveform yog qhov tob.
Q3 thiab Q4 yog siv los muab cov tsav tam sim no. Thaum qhib, Q3 thiab Q4 tsuas muaj qhov tsawg kawg nkaus voltage poob ntawm Vce txheeb ze rau Vh thiab GND. Qhov kev poob qis no feem ntau tsuas yog kwv yees li 0.3V, uas yog qis dua Vce ntawm 0.7V.
R5 thiab R6 yog cov lus tawm tswv yim, siv los ua piv txwv lub rooj vag voltage. Cov qauv ntsuas hluav taws xob tsim cov lus tawm tswv yim tsis zoo rau lub hauv paus ntawm Q1 thiab Q2 txog Q5, yog li txwv lub rooj vag hluav taws xob rau tus nqi tsawg. Tus nqi no tuaj yeem hloov kho los ntawm R5 thiab R6.
Thaum kawg, R1 muab lub hauv paus txwv tam sim no rau Q3 thiab Q4, thiab R4 muab lub rooj vag tam sim no txwv rau MOSFET, uas yog qhov txwv ntawm Ice ntawm Q3 thiab Q4. Yog hais tias tsim nyog, lub acceleration capacitor tuaj yeem txuas nrog rau tib lub R4.
Lub Circuit Court no muab cov yam ntxwv hauv qab no:
1. Siv cov hluav taws xob qis thiab PWM los tsav lub siab MOSFET.
2. Siv lub me me amplitude PWM teeb liab tsav lub MOSFET nrog lub rooj vag siab voltage.
3. Peak txwv ntawm qhov rooj voltage
4. Input thiab output tam sim no txwv
5. Los ntawm kev siv cov resistors tsim nyog, kev siv hluav taws xob tsawg heev tuaj yeem ua tiav.
6. PWM teeb liab yog inverted. NMOS tsis xav tau qhov tshwj xeeb no thiab tuaj yeem daws tau los ntawm kev tso lub inverter rau pem hauv ntej.
Thaum tsim cov khoom siv portable thiab cov khoom siv wireless, kev txhim kho cov khoom ua tau zoo thiab txuas ntxiv roj teeb lub neej yog ob qho teeb meem uas tus tsim qauv yuav tsum tau ntsib. DC-DC converters muaj qhov zoo ntawm kev ua haujlwm siab, cov zis loj tam sim no, thiab tsis tshua muaj quiescent tam sim no, ua rau lawv tsim nyog rau cov khoom siv hluav taws xob. Tam sim no, cov qauv tseem ceeb hauv kev txhim kho DC-DC converter tsim thev naus laus zis yog: (1) Kev siv tshuab ntau zaus: Raws li kev hloov pauv ntau zaus, qhov loj ntawm qhov hloov pauv hloov pauv kuj txo, lub zog ceev kuj tseem nce ntxiv, thiab cov lus teb dynamic tau txhim kho. . Qhov hloov zaus ntawm lub zog qis DC-DC converters yuav nce mus rau qib megahertz. (2) Kev siv hluav taws xob tsawg tsawg: Nrog kev txhim kho txuas ntxiv ntawm cov khoom siv hluav taws xob semiconductor, kev khiav hauj lwm voltage ntawm microprocessors thiab cov khoom siv hluav taws xob portable tau qis dua thiab qis dua, uas yuav tsum muaj DC-DC converters yav tom ntej los muab cov zis hluav taws xob tsawg los hloov mus rau microprocessors. cov kev xav tau rau processors thiab portable electronic devices.
Txoj kev loj hlob ntawm cov thev naus laus zis no tau muab cov kev xav tau siab dua rau kev tsim hluav taws xob chip circuits. Ua ntej ntawm tag nrho cov, raws li qhov hloov zaus txuas ntxiv mus, cov kev xav tau siab tau muab tso rau ntawm qhov kev ua tau zoo ntawm kev hloov cov ntsiab lus. Nyob rau tib lub sijhawm, cov khoom sib txuas sib txuas ntawm cov khoom siv tsav tsheb yuav tsum tau muab los xyuas kom meej tias cov khoom hloov pauv ua haujlwm ib txwm nyob ntawm kev hloov pauv mus txog MHz. Qhov thib ob, rau cov khoom siv hluav taws xob siv hluav taws xob siv hluav taws xob, kev ua haujlwm hluav taws xob ntawm lub voj voog qis (kev siv cov roj teeb lithium ua piv txwv, kev ua haujlwm voltage yog 2.5 ~ 3.6V), yog li ntawd, kev ua haujlwm voltage ntawm lub hwj chim nti yog tsawg.
MOSFET muaj kev tiv thaiv qis heev thiab siv zog tsawg. MOSFET feem ntau yog siv los ua lub zog hloov hauv cov khoom siv hluav taws xob tam sim no nrov DC-DC chips. Txawm li cas los xij, vim muaj qhov loj me me ntawm MOSFET, lub rooj vag capacitance ntawm NMOS hloov cov raj feem ntau yog siab li kaum tawm picofarads. Qhov no tso rau pem hauv ntej cov kev xav tau ntau dua rau kev tsim cov kev ua haujlwm siab zaus DC-DC converter switching tube tsav Circuit Court.
Hauv kev tsim hluav taws xob qis ULSI, muaj ntau yam ntawm CMOS thiab BiCMOS logic circuits siv bootstrap boost structures thiab tsav circuits raws li qhov loj capacitive loads. Cov kab hluav taws xob no tuaj yeem ua haujlwm ib txwm nrog lub zog hluav taws xob qis dua 1V, thiab tuaj yeem ua haujlwm ntawm ntau zaus ntawm kaum ntawm megahertz lossis ntau pua megahertz nrog lub peev xwm ntawm 1 txog 2pF. Kab lus no siv lub bootstrap boost circuit los tsim ib lub voj voog tsav nrog lub peev xwm loj load capacitance tsav uas tsim nyog rau cov tsis tshua muaj hluav taws xob, siab hloov zaus boost DC-DC converters. Lub Circuit Court yog tsim los ntawm Samsung AHP615 BiCMOS txheej txheem thiab txheeb xyuas los ntawm Hspice simulation. Thaum cov khoom siv hluav taws xob yog 1.5V thiab lub peev xwm thauj khoom yog 60pF, kev ua haujlwm zaus tuaj yeem ncav cuag ntau dua 5MHz.
cov
MOSFET hloov cov yam ntxwv
cov
1. Cov yam ntxwv zoo li qub
Raws li qhov hloov pauv, MOSFET kuj ua haujlwm hauv ob lub xeev: tawm lossis qhib. Txij li thaum MOSFET yog cov khoom siv hluav taws xob tswj hluav taws xob, nws lub xeev ua haujlwm feem ntau yog txiav txim siab los ntawm lub rooj vag-qhov voltage uGS.
Cov yam ntxwv ua haujlwm yog raws li nram no:
※ uGS＜ tig-on voltage UT: MOSFET ua haujlwm hauv thaj chaw txiav tawm, qhov ntws tawm tam sim no iDS yog qhov pib 0, qhov tso zis hluav taws xob uDS≈ UDD, thiab MOSFET nyob rau hauv lub xeev "tawm".
※ uGS> Tig-on voltage UT: MOSFET ua haujlwm hauv cheeb tsam conduction, ntws-qhov tam sim no iDS = UDD / (RD + rDS). Ntawm lawv, rDS yog qhov dej ntws tawm thaum lub MOSFET qhib. Cov zis voltage UDS = UDD?rDS/(RD+rDS), yog rDS＜＜RD, uDS≈0V, MOSFET nyob rau hauv lub xeev "on".
2. Cov yam ntxwv dynamic
MOSFET tseem muaj cov txheej txheem kev hloov pauv thaum hloov ntawm lub xeev thiab tawm, tab sis nws cov yam ntxwv muaj zog feem ntau yog nyob ntawm lub sijhawm yuav tsum tau them thiab tso tawm qhov tsis muaj peev xwm cuam tshuam nrog lub voj voog, thiab cov nqi sib txuas thiab tawm thaum lub raj nws tus kheej yog nyob rau thiab tawm. Lub sij hawm dissipation tsawg heev.
Thaum lub input voltage ui hloov ntawm siab mus rau qis thiab MOSFET hloov ntawm lub xeev mus rau lub xeev tawm, lub hwj chim mov UDD tsub lub stray capacitance CL los ntawm RD, thiab lub sij hawm them tas li τ1 = RDCL. Yog li ntawd, cov zis voltage uo yuav tsum tau mus los ntawm ib tug tej yam ncua sij hawm ua ntej hloov los ntawm qis theem mus rau theem siab; Thaum lub input voltage ui hloov ntawm qis mus rau siab thiab MOSFET hloov ntawm lub xeev tawm mus rau hauv lub xeev, tus nqi ntawm cov stray capacitance CL dhau los ntawm rDS Discharge tshwm sim nrog lub sij hawm tso tawm tas li τ2≈rDSCL. Nws tuaj yeem pom tias qhov tso zis hluav taws xob Uo kuj xav tau kev ncua sijhawm ua ntej nws tuaj yeem hloov mus rau qib qis. Tab sis vim hais tias rDS tsawg dua li RD, lub sij hawm hloov dua siab tshiab los ntawm kev txiav tawm mus rau conduction yog luv dua lub sij hawm hloov dua siab tshiab los ntawm conduction mus rau kev txiav tawm.
Txij li thaum lub qhov dej-qhov kev tiv thaiv rDS ntawm MOSFET thaum nws tig rau yog loj dua qhov saturation tsis kam rCES ntawm lub transistor, thiab sab nraud ntws tsis kam RD kuj loj dua li cov collector kuj RC ntawm lub transistor, lub sij hawm them thiab tawm. ntawm MOSFET ntev dua, ua rau MOSFET Qhov kev hloov ceev yog qis dua li ntawm transistor. Txawm li cas los xij, nyob rau hauv CMOS circuits, txij li thaum lub charger Circuit Court thiab lub discharge Circuit Court yog ob qho tib si tsis tshua muaj hluav taws xob circuits, lub them thiab tawm cov txheej txheem kuj ceev, uas ua rau ib tug high switching ceev rau CMOS Circuit Court.
Post lub sij hawm: Apr-15-2024
