xov xwm

Cov capacitors yog ib qho ntawm cov khoom siv feem ntau siv rau hauv Circuit Court boards.Raws li tus naj npawb ntawm cov khoom siv hluav taws xob (los ntawm cov xov tooj ntawm tes mus rau lub tsheb) tseem nce ntxiv, yog li qhov kev thov rau cov capacitors puas.Covid 19 kev sib kis tau cuam tshuam cov khoom siv thoob ntiaj teb los ntawm cov khoom siv semiconductors. mus rau passive Cheebtsam, thiab capacitor tau nyob rau hauv luv mov1.
Kev sib tham txog lub ntsiab lus ntawm cov capacitors tuaj yeem hloov tau yooj yim rau hauv phau ntawv lossis phau ntawv txhais lus. Ua ntej, muaj ntau hom capacitors, xws li electrolytic capacitors, film capacitors, ceramic capacitors thiab lwm yam.Tom qab ntawd, nyob rau hauv tib hom, muaj ntau yam sib txawv. Cov ntaub ntawv dielectric.Nws kuj muaj cov chav kawm sib txawv.Raws li cov qauv ntawm lub cev, muaj ob lub davhlau ya nyob twg thiab peb lub davhlau ya nyob twg capacitor hom.Nws tseem muaj X2Y hom capacitor, uas yog qhov tseem ceeb ntawm ib khub Y capacitors encapsulated hauv ib qho.Dab tsi txog supercapacitor. ?Qhov tseeb yog, yog tias koj zaum thiab pib nyeem cov lus qhia kev xaiv capacitor los ntawm cov tuam txhab loj, koj tuaj yeem yooj yim siv hnub!
Txij li cov kab lus no yog hais txog cov hauv paus, kuv yuav siv ib txoj kev sib txawv raws li niaj zaus.Raws li tau hais ua ntej, cov lus qhia kev xaiv capacitor tuaj yeem pom tau yooj yim ntawm cov chaw muag khoom 3 thiab 4, thiab cov engineers teb feem ntau tuaj yeem teb cov lus nug feem ntau txog capacitors.Hauv kab lus no, Kuv yuav tsis rov hais dua qhov koj tuaj yeem nrhiav tau hauv Is Taws Nem, tab sis yuav ua qauv qhia yuav ua li cas xaiv thiab siv cov capacitors los ntawm kev ua piv txwv.Qee yam tsis paub txog kev xaiv capacitor, xws li capacitance degradation, kuj yuav raug them.Tom qab nyeem tsab xov xwm no, koj yuav tsum muaj kev nkag siab zoo ntawm kev siv cov capacitors.
Ntau xyoo dhau los, thaum kuv ua haujlwm hauv ib lub tuam txhab uas tsim cov khoom siv hluav taws xob, peb muaj lus nug rau ib tus kws tshaj lij hluav taws xob hluav taws xob. Ntawm daim duab schematic ntawm cov khoom uas twb muaj lawm, peb yuav nug cov neeg tuaj sib tw "Dab tsi yog txoj haujlwm ntawm DC txuas electrolytic. capacitor?" thiab "Dab tsi yog kev ua haujlwm ntawm ceramic capacitor nyob ib sab ntawm lub nti?" Peb cia siab tias cov lus teb raug yog DC bus capacitor Siv rau lub zog cia, ceramic capacitor yog siv rau lim.
Cov lus teb "yog" peb nrhiav tau tiag tiag qhia tau tias txhua tus neeg hauv pab pawg tsim tau saib cov capacitors los ntawm qhov yooj yim Circuit Court foundations, tsis yog los ntawm ib qho kev xav ntawm kev xav.Qhov kev xav ntawm Circuit Court txoj kev xav tsis yog yuam kev.Ntawm frequencies (los ntawm ob peb kHz. mus rau ob peb MHz), Circuit Court txoj kev xav feem ntau tuaj yeem piav qhia qhov teeb meem zoo.Qhov no yog vim hais tias ntawm qis zaus, lub teeb liab feem ntau yog nyob rau hauv kev sib txawv hom.Siv Circuit Court txoj kev xav, peb tuaj yeem pom cov capacitor qhia hauv daim duab 1, qhov sib npaug series kuj ( ESR) thiab sib npaug series inductance (ESL) ua rau impedance ntawm lub capacitor hloov nrog zaus.
Cov qauv no piav qhia tag nrho cov kev ua tau zoo hauv Circuit Court thaum lub voj voog hloov maj mam.Txawm li cas los xij, raws li qhov zaus nce, txhua yam ua ntau thiab nyuaj.Thaum qee lub sijhawm, cov khoom siv pib qhia tsis yog-linearity.Thaum qhov zaus nce, cov qauv LCR yooj yim. muaj nws cov kev txwv.
Niaj hnub no, yog tias kuv raug nug tib lo lus nug sib tham, kuv yuav hnav kuv qhov kev tshawb xav tsom iav tsom iav thiab hais tias ob hom capacitor yog cov khoom siv hluav taws xob.Qhov txawv yog tias electrolytic capacitors tuaj yeem khaws ntau lub zog ntau dua li ceramic capacitor.Tab sis hais txog lub zog xa mus. , ceramic capacitors tuaj yeem xa hluav taws xob sai dua.Qhov no piav qhia vim li cas ceramic capacitors yuav tsum tau muab tso rau ib sab ntawm lub nti, vim tias cov nti muaj qhov hloov pauv ntau dua thiab hloov ceev piv rau lub zog hluav taws xob loj.
Los ntawm qhov kev xav no, peb tuaj yeem txhais tau ob qho qauv kev ua tau zoo rau cov capacitors.Ib qho yog lub zog npaum li cas lub capacitor tuaj yeem khaws cia, thiab lwm qhov yog qhov ceev npaum li cas lub zog no tuaj yeem hloov pauv.Ob yam nyob ntawm kev tsim cov txheej txheem ntawm lub capacitor, cov khoom siv dielectric, kev sib txuas nrog lub capacitor, thiab lwm yam.
Thaum qhov hloov pauv hauv Circuit Court raug kaw (saib daim duab 2), nws qhia tias lub load xav tau lub zog los ntawm lub hwj chim qhov chaw.Qhov ceev ntawm qhov kev hloov no kaw txiav txim siab qhov ceev ntawm lub zog xav tau.Vim lub zog mus ntawm qhov ceev ntawm lub teeb (ib nrab qhov ceev ntawm lub teeb nyob rau hauv FR4 cov ntaub ntawv), nws yuav siv sij hawm lub sij hawm mus hloov lub zog.Ntxiv, muaj ib tug impedance mismatch ntawm qhov chaw thiab cov kis tau tus mob kab thiab lub load.Qhov no txhais tau hais tias lub zog yuav tsis tau pauv nyob rau hauv ib qho kev mus ncig, tab sis nyob rau hauv ntau yam. ncig ncig mus ncig 5, uas yog vim li cas thaum lub hloov pauv hloov nrawm, peb pom kev qeeb thiab lub suab nrov hauv qhov hloov pauv waveform.
Daim duab 2: Nws siv sijhawm rau lub zog los nthuav tawm hauv qhov chaw; impedance mismatch ua rau ntau qhov kev mus ncig ntawm lub zog hloov pauv.
Qhov tseeb tias lub zog hloov pauv yuav siv sij hawm thiab ntau qhov kev mus ncig ua si qhia peb tias peb yuav tsum nrhiav cov khoom siv hluav taws xob kom ze rau qhov chaw thau khoom li sai tau, thiab peb yuav tsum nrhiav txoj hauv kev los hloov lub zog sai sai.Qhov thawj zaug feem ntau ua tiav los ntawm kev txo lub cev. Qhov kev ncua deb ntawm lub load, hloov thiab capacitor.Qhov tom kawg yog ua tiav los ntawm kev sib sau ua ke ntawm ib pawg ntawm cov capacitor nrog qhov tsawg tshaj plaws impedance.
Field txoj kev xav kuj piav qhia txog dab tsi ua rau lub suab nrov nrov.In luv luv, hom suab nrov yog generated thaum lub zog xav tau ntawm lub load tsis tau raws li lub sij hawm switching.Yog li ntawd, lub zog khaws cia nyob rau hauv qhov chaw ntawm lub load thiab nyob ze conductors yuav muab los txhawb. cov kauj ruam xav tau.Qhov chaw nruab nrab ntawm cov khoom thauj thiab cov neeg nyob ze yog qhov peb hu ua parasitic/mutual capacitance (saib daim duab 2).
Peb siv cov piv txwv hauv qab no los qhia txog kev siv electrolytic capacitors, multilayer ceramic capacitors (MLCC), thiab zaj duab xis capacitors.Ob Circuit Court thiab field theory yog siv los piav qhia txog kev ua tau zoo ntawm cov capacitors xaiv.
Electrolytic capacitor feem ntau yog siv nyob rau hauv DC txuas raws li lub ntsiab lub zog.Qhov kev xaiv ntawm electrolytic capacitor feem ntau nyob ntawm:
Rau EMC kev ua tau zoo, cov yam ntxwv tseem ceeb tshaj plaws ntawm cov capacitors yog impedance thiab zaus yam ntxwv.Low-frequency conducted emissions ib txwm nyob ntawm qhov kev ua tau zoo ntawm DC txuas capacitor.
Lub impedance ntawm DC txuas tsis tsuas yog nyob ntawm ESR thiab ESL ntawm lub capacitor, tab sis kuj nyob rau thaj tsam ntawm lub voj voog thermal, raws li pom hauv daim duab 3.Ib qhov loj dua thermal voj cheeb tsam txhais tau hais tias lub zog hloov mus ntev dua, yog li kev ua tau zoo. yuav raug cuam tshuam.
Ib kauj ruam-down DC-DC converter tau tsim los ua pov thawj qhov no.Qhov kev teeb tsa ua ntej EMC kuaj pom nyob rau hauv daim duab 4 ua ib qho kev ntsuas emissions ntawm 150kHz thiab 108MHz.
Nws yog ib qho tseem ceeb los xyuas kom meej tias cov capacitors siv nyob rau hauv cov ntaub ntawv kawm no yog tag nrho los ntawm tib lub chaw tsim tshuaj paus kom tsis txhob muaj qhov sib txawv ntawm impedance yam ntxwv.Thaum soldering lub capacitor ntawm PCB, xyuas kom meej tias tsis muaj ntev leads, vim qhov no yuav ua rau kom cov ESL ntawm. lub capacitor.Daim duab 5 qhia txog peb qhov kev teeb tsa.
Cov txiaj ntsig tau ua tawm ntawm peb qhov kev teeb tsa no tau pom hauv daim duab 6.Nws tuaj yeem pom tau tias, piv nrog ib qho 680 µF capacitor, ob lub 330 µF capacitors ua tiav lub suab nrov txo kev ua tau zoo ntawm 6 dB dhau qhov ntau zaus.
Los ntawm txoj kev xav ntawm lub voj voog, nws tuaj yeem hais tau tias los ntawm kev sib txuas ob lub capacitors nyob rau hauv parallel, ob qho tib si ESL thiab ESR yog halved.Los ntawm qhov kev xav ntawm qhov kev xav, tsis tsuas yog ib qho khoom siv hluav taws xob xwb, tab sis ob qho khoom siv hluav taws xob tau muab rau tib lub zog. Txawm li cas los xij, ntawm cov zaus ntau dua, qhov sib txawv ntawm ob lub 330 µF capacitor thiab ib qho 680 µF capacitor yuav shrink.Qhov no yog vim lub suab nrov nrov qhia tias tsis txaus cov kauj ruam lub zog teb.Thaum txav lub 330 µF capacitor los ze zog rau. qhov hloov pauv, peb txo lub sijhawm hloov hluav taws xob, uas ua rau kom cov kauj ruam teb ntawm lub capacitor.
Qhov tshwm sim qhia peb ib zaj lus qhia tseem ceeb heev.Kev nce lub peev xwm ntawm ib lub capacitor feem ntau yuav tsis txhawb cov kauj ruam thov kom muaj zog ntxiv.Yog tias ua tau, siv qee qhov me me capacitive Cheebtsam.Nws muaj ntau yam zoo rau qhov no.Qhov thawj yog tus nqi. Feem ntau. hais lus, rau tib lub pob loj, tus nqi ntawm lub capacitor nce exponentially nrog tus nqi capacitance.Siv ib lub capacitor yuav kim dua li siv ob peb lub capacitors me me.Qhov thib ob yog vim li cas loj.Qhov kev txwv ntawm cov khoom tsim feem ntau yog qhov siab. ntawm lub Cheebtsam.Rau qhov loj-tswj capacitors, qhov siab yog feem ntau loj heev rau cov khoom tsim.Qhov thib peb yog vim li cas EMC kev ua tau zoo peb pom nyob rau hauv cov ntaub ntawv kawm.
Lwm qhov tseem ceeb uas yuav tsum tau xav txog thaum siv lub tshuab hluav taws xob electrolytic yog tias thaum koj txuas ob lub capacitor hauv series los qhia qhov voltage, koj yuav xav tau qhov ntsuas qhov ntsuas 6.
Raws li tau hais ua ntej, ceramic capacitors yog cov khoom siv me me uas tuaj yeem muab lub zog sai sai.Kuv tau nug cov lus nug "Kuv xav tau capacitor ntau npaum li cas?" Cov lus teb rau lo lus nug no yog tias rau ceramic capacitors, tus nqi capacitance yuav tsum tsis yog qhov tseem ceeb. Qhov kev txiav txim siab tseem ceeb ntawm no yog los txiav txim siab qhov zaus ntawm lub zog hloov pauv ceev txaus rau koj daim ntawv thov.Yog tias qhov kev ua haujlwm tsis zoo ntawm 100 MHz, ces lub capacitor nrog qhov tsawg tshaj plaws impedance ntawm 100 MHz yuav yog qhov kev xaiv zoo.
Qhov no yog lwm qhov kev to taub yuam kev ntawm MLCC.Kuv tau pom cov engineers siv ntau lub zog xaiv ceramic capacitors nrog qis tshaj ESR thiab ESL ua ntej txuas cov capacitors rau RF siv taw tes los ntawm cov kab ntev ntev.Nws yog tsim nyog hais tias ESL ntawm MLCC feem ntau yog ntau ntau. qis dua qhov kev sib txuas inductance ntawm lub rooj tsavxwm.Kev sib txuas inductance tseem yog qhov tseem ceeb tshaj plaws uas cuam tshuam rau lub siab zaus impedance ntawm ceramic capacitors7.
Daim duab 7 qhia txog qhov piv txwv tsis zoo.Ntev kab (0.5 ntiv tes ntev) qhia yam tsawg kawg 10nH inductance.Qhov kev simulation tshwm sim qhia tau hais tias qhov impedance ntawm lub capacitor ua ntau dua qhov xav tau ntawm qhov zaus taw tes (50 MHz).
Ib qho ntawm cov teeb meem nrog MLCCs yog tias lawv zoo li resonate nrog cov qauv inductive ntawm lub rooj tsavxwm.Qhov no tuaj yeem pom hauv qhov piv txwv pom hauv daim duab 8, qhov twg siv 10 µF MLCC qhia txog resonance ntawm kwv yees li 300 kHz.
Koj tuaj yeem txo qis resonance los ntawm kev xaiv ib qho kev tivthaiv nrog ESR loj dua lossis tsuas yog tso tus nqi me me (xws li 1 ohm) hauv cov koob nrog lub capacitor.Cov hom no siv cov khoom tsis zoo los tiv thaiv lub system.Lwm txoj kev yog siv lwm lub capacitance. tus nqi txav lub resonance mus rau qis dua lossis siab dua resonance point.
Zaj duab xis capacitors yog siv nyob rau hauv ntau daim ntawv thov.Lawv yog cov capacitors ntawm kev xaiv rau high-power DC-DC converters thiab yog siv raws li EMI suppression lim nyob rau hauv lub hwj chim kab (AC thiab DC) thiab hom-hom lim configurations.Peb coj ib tug X capacitor raws li ib qho piv txwv los piav qhia txog qee cov ntsiab lus tseem ceeb ntawm kev siv zaj duab xis capacitors.
Yog tias muaj qhov tshwm sim tshwm sim, nws yuav pab txo qhov siab tshaj qhov siab ntawm txoj kab, yog li nws feem ntau yog siv nrog lub zog hluav taws xob hloov pauv (TVS) lossis hlau oxide varistor (MOV).
Tej zaum koj twb paub tag nrho cov no, tab sis koj puas paub tias tus nqi capacitance ntawm X capacitor tuaj yeem txo qis nrog xyoo ntawm kev siv? X capacitor tsuas yog poob rau ob peb feem pua ​​​​ntawm nws cov nqi ntsuas hauv ib xyoos lossis ob xyoos, yog li lub kaw lus pib tsim nrog X capacitor tiag tiag poob tag nrho cov kev tiv thaiv uas lub hauv ntej-kawg capacitor yuav muaj.
Yog li, dab tsi tshwm sim? Cov huab cua noo tuaj yeem nkag mus rau hauv lub capacitor, nce cov xaim thiab nruab nrab ntawm lub thawv thiab cov epoxy potting compound.Lub aluminium metallization tuaj yeem oxidized.Alumina yog ib qho hluav taws xob zoo insulator, yog li txo cov capacitance.Qhov no yog ib qho teeb meem uas. tag nrho cov zaj duab xis capacitors yuav ntsib.Qhov teeb meem kuv hais txog yog zaj duab xis thickness.Reputable capacitor hom siv thicker films, ua rau cov capacitors loj dua lwm hom.Cov zaj duab xis nyias ua rau lub capacitor tsis muaj zog rau overload (voltage, tam sim no, los yog kub), thiab nws tsis zoo li yuav kho nws tus kheej.
Yog tias X capacitor tsis txuas mus tas li rau lub zog hluav taws xob, ces koj tsis tas yuav txhawj xeeb. Piv txwv li, rau cov khoom lag luam uas muaj qhov hloov pauv nyuaj ntawm lub zog hluav taws xob thiab lub capacitor, qhov loj me yuav tseem ceeb dua lub neej, thiab Tom qab ntawd koj tuaj yeem xaiv lub thinner capacitor.
Txawm li cas los xij, yog tias lub capacitor txuas mus tas li mus rau lub zog hluav taws xob, nws yuav tsum muaj kev ntseeg siab heev.Qhov oxidation ntawm capacitors tsis yog kev zam.Yog tias cov khoom siv capacitor epoxy yog cov khoom zoo thiab cov capacitor tsis feem ntau raug rau qhov kub thiab txias, qhov poob hauv tus nqi yuav tsum tsawg.
Hauv tsab xov xwm no, thawj zaug tau qhia txog qhov kev xav pom ntawm cov capacitors.Cov piv txwv thiab cov txiaj ntsig simulation qhia tau tias yuav xaiv thiab siv hom capacitor li cas.Vam tias cov ntaub ntawv no tuaj yeem pab koj nkag siab txog lub luag haujlwm ntawm capacitors hauv hluav taws xob thiab EMC tsim ntau dua.
Dr. Min Zhang yog tus tsim thiab tus thawj coj EMC tus kws pab tswv yim ntawm Mach One Design Ltd, lub tuam txhab ua vaj tsev nyob hauv UK tshwj xeeb hauv EMC kev sab laj, kev daws teeb meem thiab kev cob qhia. cov tuam txhab thoob ntiaj teb.
Hauv Kev Ua Raws Cai yog qhov tseem ceeb ntawm cov xov xwm, cov ntaub ntawv, kev kawm thiab kev tshoov siab rau cov kws tshaj lij hluav taws xob thiab hluav taws xob engineering.
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