MOSFET yepakutanga ruzivo rwekutanga uye kushandisa

Nekuda kwekuti sei depletion modeMOSFETshazvina kushandiswa, hazvikurudzirwe kusvika pazasi payo.

Kune aya maviri ekusimudzira-modhi MOSFETs, NMOS inonyanya kushandiswa. Chikonzero ndechekuti pa-resistance idiki uye iri nyore kugadzira. Naizvozvo, NMOS inowanzo shandiswa mukuchinja magetsi uye mota drive application. Mukusuma kunotevera, NMOS inonyanya kushandiswa.

Pane parasitic capacitance pakati pemapini matatu eMOSFET. Izvi hazvisi izvo zvatinoda, asi zvinokonzerwa nekugadzirisa maitiro ekugadzirisa. Kuvapo kweparasitic capacitance kunoita kuti iwedzere kunetsa pakugadzira kana kusarudza dhiraivha yedhiraivha, asi hapana nzira yekuidzivirira. Tichasuma zvakadzama gare gare.

Pane diode yeparasitic pakati pedhireni uye sosi. Izvi zvinonzi body diode. Iyi diode yakakosha zvakanyanya kana uchityaira inductive mitoro (senge mota). Nenzira, iyo diode yemuviri inongowanikwa mune imwechete MOSFET uye kazhinji haiwanikwe mukati meiyo yakabatanidzwa yedunhu chip.

 

2. MOSFET conduction maitiro

Kuitisa zvinoreva kuita sechichinjiko, icho chakaenzana nekuvharwa kwekuchinja.

Hunhu hweNMOS ndehwekuti inobatika kana Vgs yakakura kupfuura imwe kukosha. Inokodzera kushandiswa kana sosi yakadzikwa (yakaderera-kuguma drive), chero bedzi gedhi remagetsi richisvika 4V kana 10V.

Hunhu hwePMOS ndehwekuti inobatika kana Vgs iri pasi pehumwe kukosha, iyo inokodzera mamiriro apo sosi yakabatana neVCC (yakakwirira-kuguma drive). Zvisinei, kunyangePMOSinogona kushandiswa nyore nyore semutyairi wepamusoro-soro, NMOS inowanzo shandiswa mumadhiraivha epamusoro-soro nekuda kwehombe pa-resistance, mutengo wepamusoro, uye mashoma ekutsiva marudzi.

 

3. MOS shandura tube kurasikirwa

Kunyangwe iri NMOS kana PMOS, pane-inopikisa mushure mekunge yabatidzwa, saka yazvino ichapedza simba pakuramba uku. Ichi chikamu chesimba rinopedzwa chinonzi conduction kurasikirwa. Kusarudza MOSFET ine diki pa-resistance inoderedza kurasikirwa kwekuita. Yanhasi yakaderera-simba MOSFET pa-kupokana kazhinji yakatenderedza makumi emamiriyoni, uye kune zvakare akati wandei mamiriyoni.

Kana MOSFET ikabatidzwa nekudzimwa, haifanirwe kupedzwa ipapo ipapo. Iyo voltage mhiri kweMOS ine maitiro ekuderera, uye ikozvino kuyerera kune kuwedzera maitiro. Munguva iyi, theMOSFET'skurasikirwa ndicho chigadzirwa chemagetsi uye chazvino, chinonzi switching loss. Kazhinji kuchinja kurasikirwa kwakakura zvakanyanya kudarika kurasikirwa kwekuita, uye nekukurumidza kuchinja kwekuchinja, ndiko kukura kwekurasikirwa.

Chigadzirwa chemagetsi uye chazvino panguva yekufambisa chakakura kwazvo, zvichikonzera kurasikirwa kukuru. Kupfupisa nguva yekuchinja kunogona kuderedza kurasikirwa panguva yega yega conduction; kuderedza kushanduka kwekuchinja kunogona kuderedza nhamba yekuchinja pane imwe nguva yeyuniti. Nzira mbiri idzi dzinogona kuderedza kurasikirwa kwekuchinja.

Iyo waveform kana MOSFET yabatidzwa. Zvinogona kuonekwa kuti chigadzirwa chemagetsi uye chazvino panguva yekufambisa chakakura kwazvo, uye kurasikirwa kunokonzerwa kwakakurawo zvikuru. Kuderedza nguva yekushandura kunogona kuderedza kurasikirwa panguva yega yega conduction; kuderedza kushanduka kwekuchinja kunogona kuderedza nhamba yekuchinja pane imwe nguva yeyuniti. Nzira mbiri idzi dzinogona kuderedza kurasikirwa kwekuchinja.

 

4. MOSFET mutyairi

Kuenzaniswa nebipolar transistors, zvinotendwa kuti hapana ikozvino inodiwa kuti ubatidze MOSFET, chero bedzi iyo GS voltage yakakwira kupfuura imwe kukosha. Izvi zviri nyore kuita, asi tinodawo kukurumidza.

Zvinogona kuonekwa muchimiro cheMOSFET kuti pane parasitic capacitance pakati peGS neGD, uye kutyaira kweMOSFET ndiko chaizvo kubhadharisa uye kubuda kwecapacitor. Kuchaja iyo capacitor inoda ikozvino, nekuti iyo capacitor inogona kutariswa sepfupi redunhu panguva yekuchaja, saka iyo pakarepo ikozvino ichave yakakura. Chinhu chekutanga kutarisisa pakusarudza / kugadzira mutyairi weMOSFET huwandu hwepakarepo pfupi-yedunhu ikozvino iyo inogona kupa. .

Chechipiri chekucherechedza ndechekuti NMOS, iyo inowanzo shandiswa pakutyaira kwepamusoro-soro, inoda kuti gedhi regedhi rive rakakura kupfuura iro vhezheni yemagetsi kana yabatidzwa. Kana iyo yepamusoro-side inotyairwa MOSFET ikabatidzwa, sosi voltage yakafanana neiyo drain voltage (VCC), saka gedhi voltage i4V kana 10V yakakura kupfuura VCC panguva ino. Kana iwe uchida kuwana voltage yakakura kupfuura VCC mune imwecheteyo sisitimu, iwe unoda yakakosha yekusimudzira dunhu. Vazhinji vatyairi vemota vakabatanidza pombi dzekuchaja. Izvo zvinofanirwa kucherechedzwa kuti yakakodzera yekunze capacitor inofanirwa kusarudzwa kuti iwane yakakwana yenguva pfupi-yedunhu ikozvino kutyaira iyo MOSFET.

 

Iyo 4V kana 10V yataurwa pamusoro ndiyo yekubatidza-voltage yeanowanzo shandiswa maMOSFET, uye hongu imwe margin inoda kubvumidzwa panguva yekugadzira. Uye iyo yakakwira voltage, inokurumidza kukurumidza kufambisa uye idiki yekupikisa conduction. Ikozvino kune maMOSFET ane madiki conduction voltages anoshandiswa munzvimbo dzakasiyana, asi mu12V mota dzemagetsi masisitimu, kazhinji 4V conduction yakakwana.

 

Kune MOSFET mutyairi wedunhu uye kurasikirwa kwayo, ndapota tarisa kune Microchip's AN799 Matching MOSFET Drivers kune MOSFETs. Yakanyatsotsanangurwa, saka handisi kuzonyora zvimwe.

 

Chigadzirwa chemagetsi uye chazvino panguva yekufambisa chakakura kwazvo, zvichikonzera kurasikirwa kukuru. Kuderedza nguva yekushandura kunogona kuderedza kurasikirwa panguva yega yega conduction; kuderedza kushanduka kwekuchinja kunogona kuderedza nhamba yekuchinja pane imwe nguva yeyuniti. Nzira mbiri idzi dzinogona kuderedza kurasikirwa kwekuchinja.

MOSFET imhando yeFET (imwe yacho JFET). Inogona kugadzirwa kuva yekusimudzira modhi kana depletion modhi, P-channel kana N-channel, huwandu hwe4 mhando. Nekudaro, chete yekusimudzira-modhi N-chiteshi MOSFET ndiyo inonyanya kushandiswa. uye yekusimudzira-rudzi rweP-channel MOSFET, saka NMOS kana PMOS inowanzo nongedzera kumhando mbiri idzi.

 

5. MOSFET application circuit?

Chinonyanya kukosha hunhu hweMOSFET hunhu hwayo hwakanaka hwekuchinja, saka inoshandiswa zvakanyanya mumaseketi anoda switch yemagetsi, sekuchinja magetsi uye madhiraivha emota, pamwe nekudzima kwemwenje.

 

Nhasi vatyairi veMOSFET vane akati wandei akakosha zvinodiwa:

1. Low voltage application

Paunenge uchishandisa 5V simba rekushandisa, kana yechinyakare totem pole chimiro ichishandiswa panguva ino, sezvo transistor be ine voltage donho rinenge 0.7V, iyo chaiyo yekupedzisira voltage inoshandiswa kugedhi inongova 4.3V. Panguva ino, tinosarudza simba regedhi rezita

Pane imwe njodzi kana uchishandisa 4.5V MOSFET. Dambudziko rimwe chetero rinoitikawo kana uchishandisa 3V kana imwe yakaderera-voltage magetsi.

2. Wide voltage application

Iyo yekupinza voltage haisi iyo yakagadziriswa kukosha, inoshanduka nenguva kana zvimwe zvinhu. Shanduko iyi inoita kuti magetsi ekufambisa anopihwa nePWM dunhu kuMOSFET asagadzikane.

Kuti uite kuti maMOSFET ave akachengeteka pasi pemagedhi emagetsi akakwira, maMOSFET mazhinji akavaka-mukati mavoltage regulators kuti adzikise nechisimba kukwirisa kwegedhi voltage. Muchiitiko ichi, kana iyo yakapihwa yekutyaira voltage ichidarika voltage yevoltage regulator chubhu, inokonzeresa mashandisiro makuru emagetsi.

Panguva imwecheteyo, kana iwe ukangoshandisa musimboti weresistor voltage division kudzikisa gedhi voltage, MOSFET inoshanda nemazvo kana magetsi ekupinza akakwira, asi kana simba rekupinza radzikiswa, gedhi regedhi rinenge risina kukwana, zvichikonzera. conduction isina kukwana, zvichibva zvawedzera kushandiswa kwesimba.

3. Dual voltage application

Mune mamwe maseketi ekudzora, iyo logic chikamu inoshandisa yakajairwa 5V kana 3.3V dhijitari voltage, nepo chikamu chemagetsi chinoshandisa voltage ye12V kana kutokwira. Iwo ma voltages maviri akabatana kune imwe nzvimbo.

Izvi zvinosimudza chinodiwa chekushandisa dunhu kuitira kuti yakaderera-voltage side inyatso kudzora iyo MOSFET padivi repamusoro-voltage. Panguva imwecheteyo, iyo MOSFET padivi repamusoro-voltage ichasanganawo nematambudziko akataurwa mu1 uye 2.

Muzviitiko zvitatu izvi, iyo totem pole chimiro haigone kuzadzisa zvinodiwa zvinobuda, uye mazhinji ari kure-pasherufu MOSFET mutyairi ICs haaite kunge anosanganisira gedhi voltage ekudzikamisa zvimiro.

 

Saka ndakagadzira dunhu rakati kuti rienderane nezvinodiwa zvitatu izvi.

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Mutyairi wedunhu reNMOS

Pano ini ndinongoita ongororo yakapusa yeNMOS mutyairi wedunhu:

Vl uye Vh ndiyo yakaderera-yekupedzisira uye yepamusoro-yekupedzisira magetsi emagetsi zvichiteerana. Iwo maviri voltages anogona kunge akafanana, asi Vl haifanire kudarika Vh.

Q1 uye Q2 inoumba inverted totem pole kuti iwane yekuzviparadzanisa nevamwe uku uchiona kuti machubhu maviri emutyairi Q3 neQ4 haabatike panguva imwe chete.

R2 uye R3 inopa iyo PWM voltage referensi. Nekushandura iyi referensi, dunhu rinogona kushandirwa munzvimbo iyo iyo PWM siginecha waveform iri kukwira.

Q3 uye Q4 inoshandiswa kupa drive ikozvino. Kana yabatidzwa, Q3 neQ4 inongove nekashoma voltage kudonha kweVce hukama neVh neGND. Uku kudonha kwemagetsi kunowanzo kungoita 0.3V chete, iyo yakaderera zvakanyanya pane Vce ye0.7V.

R5 neR6 ndezvipikisi zvemhinduro, zvinoshandiswa kuenzanisa magetsi egedhi. Iyo sampled voltage inoburitsa yakasimba yakaipa mhinduro kune zvigadziko zveQ1 uye Q2 kuburikidza neQ5, nekudaro ichidzikamisa gedhi voltage kune yakaderera kukosha. Kukosha uku kunogona kugadziriswa kuburikidza neR5 neR6.

Chekupedzisira, R1 inopa hwaro hwazvino muganho weQ3 neQ4, uye R4 inopa gedhi ikozvino muganho weMOSFET, unova muganho weIce yeQ3 neQ4. Kana zvichidikanwa, acceleration capacitor inogona kubatanidzwa mukufanana neR4.

Saiti iyi inopa zvinotevera zvinhu:

1. Shandisa yakaderera-side voltage uye PWM kutyaira yepamusoro-side MOSFET.

2. Shandisa diki amplitude PWM chiratidzo kutyaira MOSFET ine yakakwirira gedhi voltage zvinodiwa.

3. Peak muganhu wegedhi voltage

4. Input and output current limits

5. Nokushandisa zvinopikisa zvakakodzera, kushandiswa kwesimba kwakaderera zvikuru kunogona kuwanikwa.

6. Chiratidzo chePWM chinopindurwa. NMOS haidi chimiro ichi uye inogona kugadziriswa nekuisa inverter pamberi.

Paunenge uchigadzira midziyo inotakurika uye zvigadzirwa zvisina waya, kuvandudza mashandiro echigadzirwa uye kuwedzera hupenyu hwebhatiri inyaya mbiri dzinofanirwa kutarisana nevagadziri. DC-DC converters ine zvakanakira kushanda kwepamusoro, yakakura kubuda ikozvino, uye yakaderera quiescent yazvino, zvichiita kuti dzive dzakakodzera kwazvo pakugonesa magetsi anotakurika. Parizvino, maitiro makuru mukuvandudzwa kweDC-DC converter design tekinoroji ndeiyi: (1) High-frequency tekinoroji: Sezvo iyo switching frequency inowedzera, saizi yekuchinja inoshandura inoderedzwa zvakare, simba remagetsi rinowedzerawo zvakanyanya, uye mhinduro ine simba inovandudzwa. . Iyo inoshandura frequency yeakaderera-simba DC-DC inoshandura inokwira kusvika padanho re megahertz. (2) Tekinoroji yakaderera yekubuda kwemagetsi: Nekuenderera mberi kwekuvandudza tekinoroji yekugadzira semiconductor, simba rekushanda remamicroprocessors uye midziyo yemagetsi inotakurika iri kuramba ichidzika nekudzika, izvo zvinoda remangwana DC-DC converters kupa yakaderera inobuda voltage kuti ienderane kune microprocessors. zvinodiwa kune mapurosesa uye inotakurika zvigadzirwa zvemagetsi.

Kuvandudzwa kwematekinoroji aya kwakaisa pamberi pepamusoro zvinodiwa pakugadzirwa kwesimba chip maseketi. Chekutanga pane zvese, sezvo frequency yekuchinja ichiramba ichiwedzera, zvinodiwa zvepamusoro zvinoiswa pakuita kwekuchinja zvinhu. Panguva imwecheteyo, inoenderana switching element drive maseketi inofanirwa kupihwa kuti ive nechokwadi chekuti zvinhu zvekuchinja zvinoshanda zvakajairika pakuchinja ma frequency kusvika kuMHz. Chechipiri, kune bhatiri-powered inotakurika zvigadzirwa zvemagetsi, iyo yekushanda voltage yedunhu yakaderera (kutora lithium mabhatiri semuenzaniso, iyo inoshanda voltage ndeye 2.5 ~ 3.6V), saka, iyo inoshanda voltage yemagetsi chip yakaderera.

 

MOSFET ine yakaderera-kupikisa uye inoshandisa yakaderera simba. MOSFET inowanzo shandiswa sechinjo yemagetsi mune yakakurumbira yakakwira-inoshanda DC-DC machipisi. Nekudaro, nekuda kwehukuru hweparasitic capacitance yeMOSFET, iyo gedhi capacitance yeNMOS switching chubhu inowanzokwira semakumi emapicofarad. Izvi zvinoisa kumberi kwepamusoro zvinodiwa dhizaini yepamusoro yekushanda frequency DC-DC inoshandura switching chubhu drive wedunhu.

Mune yakaderera-voltage ULSI dhizaini, kune akasiyana eCMOS uye BiCMOS logic maseketi anoshandisa bootstrap boost zvimiro uye dhiraivha maseketi semahombe capacitive mitoro. Aya maseketi anogona kushanda zvakajairwa nemagetsi emagetsi ari pasi pe1V, uye anogona kushanda pa frequency yemakumi e megahertz kana kunyange mazana e megahertz ine mutoro we 1 kusvika 2pF. Ichi chinyorwa chinoshandisa bootstrap boost circuit kugadzira dhiraivha yedhiraivha ine hombe capacitance drive kugona iyo inokodzera yakaderera voltage, yakakwirira switching frequency inosimudzira DC-DC converters. Dunhu rakagadzirwa zvichibva pane Samsung AHP615 BiCMOS maitiro uye yakasimbiswa neHspice simulation. Kana magetsi ekupa ari 1.5V uye simba rekutakura riri 60pF, nguva yekushanda inogona kusvika kupfuura 5MHz.

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MOSFET kuchinja maitiro

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1. Static maitiro

Sechinhu chinoshandura, MOSFET inoshandawo mumatunhu maviri: kudzima kana kubatidzwa. Sezvo MOSFET chiri chinhu chinodzorwa nemagetsi, mamiriro ayo ekushanda anonyanya kutsanangurwa negedhi-source voltage uGS.

 

Maitiro ekushanda ndeaya anotevera:

※ uGS＜turn-on voltage UT: MOSFET inoshanda munzvimbo yakachekwa, iyo drain-source yazvino iDS ndeye 0, inobuda voltage uDS≈UDD, uye MOSFET iri mu "off" state.

※ uGS> Turn-on voltage UT: MOSFET inoshanda munzvimbo yekuitisa, drain-source current iDS=UDD/(RD+rDS). Pakati pavo, rDS ndeyekudonhedza-sosi kuramba kana MOSFET ikabatidzwa. Iyo yakabuda voltage UDS=UDD?rDS/(RD+rDS), kana rDS＜＜RD, uDS≈0V, MOSFET iri mu "on" state.

2. Dynamic maitiro

MOSFET zvakare ine shanduko yekuchinja kana ichichinja pakati pekudzima nekudzima nyika, asi maitiro ayo ane simba anonyanya kuenderana nenguva inodiwa kubhadharisa uye kuburitsa iyo yakarasika capacitance ine chekuita nedunhu, uye kuunganidza kwechaji uye kuburitsa kana chubhu pachayo ichibatidzwa nekudzimwa. Nguva yekubvisa idiki kwazvo.

Kana magetsi ekuisa ui achinge achinja kubva kumusoro kuenda pasi uye MOSFET yachinja kubva kudunhu kuenda kunze kwenyika, magetsi eUDD anochaja yakarasika capacitance CL kuburikidza neRD, uye nguva yekuchaja inogara τ1=RDCL. Naizvozvo, iyo inobuda voltage uo inoda kupfuura nekumwe kunonoka isati yachinja kubva padanho rakaderera kuenda padanho repamusoro; apo magetsi ekuisa ui achinja kubva pasi kuenda kumusoro uye MOSFET ichichinja kubva kuoff state kuenda kudunhu, kubhadharisa pane rakarasika capacitance CL inopfuura ne rDS Discharge inoitika nenguva yekuburitsa nguva dzose τ2≈rDSCL. Zvinogona kuoneka kuti iyo inobuda voltage Uo inodawo imwe kunonoka isati yagona kuchinjika kusvika padanho rakaderera. Asi nekuda kwekuti rDS idiki pane RD, nguva yekushandura kubva pakucheka-kubva kune conduction ipfupi pane yekutendeuka nguva kubva mukuitisa kuenda kuchekwa.

Sezvo iyo drain-source resistance rDS yeMOSFET painobatidzwa yakakura kudarika saturation resistance rCES ye transistor, uye iyo yekunze drain resistance RD yakakurawo kudarika muunganidzi kuramba RC yetransistor, nguva yekuchaja uye yekuburitsa. yeMOSFET yakarebesa, ichiita MOSFET Iyo yekumhanyisa yekuchinja yakadzikira pane yetransistor. Nekudaro, mumaseketi eCMOS, sezvo dunhu rekuchaja uye dunhu rekuburitsa ese ari maviri-anodzivirira maseketi, maitiro ekuchaja uye ekuburitsa ari kukurumidza, zvichikonzera kukurumidza kushandura kwedunhu reCMOS.