Open-collector outputs muaj ntau zuj zus nyob rau hauv cov chip designs, ua hauj lwm amplifiers, thiab microcontroller (Arduino) hom kev siv rau kev sib txuas nrog lwm yam circuits los yog tsav high-tam sim no load tswj circuits xws li leds thiab relays uas tej zaum yuav incompatible nrog hluav taws xob yam ntxwv. Tab sis "qhib collector" txhais li cas, thiab peb tuaj yeem siv nws li cas hauv kev tsim hluav taws xob?
Raws li peb paub los ntawm peb cov kev qhia yav dhau los, bipolar junction transistors, txawm tias NPN lossis PNP, yog peb lub davhlau ya nyob twg. Peb lub terminals raug txheeb xyuas tias Emitter, Base, thiab Collector.
Peb tuaj yeem siv bipolar transistors los ua haujlwm ua amplifiers, piv txwv li qhov amplitude ntawm lub teeb liab tso zis ntau dua lub teeb liab input, los yog, feem ntau, raws li solid-state "on / off" hom hluav taws xob keyboards.
Vim hais tias lub bipolar hlws ris transistor (BJT) yog ib tug 3-terminal ntaus ntawv, nws yuav configured thiab ua hauj lwm nyob rau hauv ib tug ntawm peb txawv switching hom. Lawv yog cov hauv paus (CB), hom emitter (CE), thiab cov khoom sib xws (CC).
Thaum siv rau amplification (chaw ua haujlwm cheeb tsam) lossis hloov pauv (txiav tawm lossis thaj chaw saturation), qhov "common emitter" configuration yog nyob deb ntawm qhov feem ntau ntawm cov transistor configuration. Qhov no yog qhov kev teeb tsa transistor peb yuav pom hauv qhov kev qhia no hais txog kev qhib cov khoom tso tawm.
Xav txog tus txheej txheem emitter amplifier configuration uas qhia hauv qab no.
Nyob rau hauv no ib-theem ib-theem-emitter configuration, cov kuj yog kev cob cog rua ntawm lub collector davhlau ya nyob twg transistor thiab lub hwj chim zoo rail V CC. Lub teeb liab input yog siv nruab nrab ntawm lub hauv paus transistor thiab emitter junction, thiab lub emitter davhlau ya nyob twg yog ncaj qha grounded. Li no cov lus piav qhia "common emitter" (CE).
Lub bias tam sim no IB yuav tsum tau "tig" lub transistor yog noj ncaj qha mus rau hauv lub hauv paus ntawm NPN transistor los ntawm lub hauv paus tsis kam RB, thiab cov zis tawm tswv yim yog thim rov qab 180 degree txheeb ze rau cov teeb liab tawm tswv yim, coj los ntawm cov khoom siv thiab cov emitter terminals.
Qhov no tso cai rau lub transistor collector tam sim no tswj ntawm xoom (txiav-tawm) thiab qee tus nqi siab tshaj (saturation). Qhov no yog tus qauv hauv kev teeb tsa emitter ntau thiab tuaj yeem ua tsis ncaj xws li A Class A amplifier lossis raws li qhov kev hloov pauv ntawm lub logic.
Qhov teeb meem ntawm no yog tias ob qho tib si transistor thiab nws cov khoom siv thauj khoom tau txuas nrog rau cov khoom siv hluav taws xob ntau. Lub collector kuj RC yog siv rau ntawm no tso cai rau lub collector voltage VC hloov nyob rau hauv cov lus teb rau cov tswv yim teeb liab siv rau lub hauv paus davhlau ya nyob twg ntawm lub transistor, yog li tso cai rau lub transistor los tsim ib tug amplified tso zis teeb liab. Txij li thaum tsis muaj RC, qhov hluav taws xob ntawm cov khoom siv hluav taws xob yuav ib txwm sib npaug rau cov khoom siv hluav taws xob.
Raws li tau hais ua ntej, thaum VBE tsawg dua {{0}} .7 volts (zero base tam sim no) lossis ntau tshaj 0.7 volts (qhov siab tshaj plaws tam sim no), lub tshuab hluav taws xob bipolar tuaj yeem ua haujlwm ntawm nws qhov kev txiav tawm thiab cheeb tsam saturation.