LED tsav nti taw qhia
Nrog txoj kev loj hlob sai ntawm kev lag luam automotive electronics, high-density LED tsav chips nrog dav input voltage ntau yog dav siv nyob rau hauv tsheb teeb pom kev zoo, nrog rau sab nrauv pem hauv ntej thiab nram qab teeb pom kev zoo, sab hauv teeb pom kev zoo thiab zaub backlighting.
LED tsav chips tuaj yeem muab faib ua analog dimming thiab PWM dimming raws li txoj kev dimming.Analog dimming yog qhov yooj yim, PWM dimming yog qhov nyuaj, tab sis cov linear dimming ntau dua analog dimming.LED tsav nti raws li chav kawm ntawm lub zog tswj nti, nws cov topology tsuas yog Buck thiab Boost.puck Circuit Court tso zis tam sim no tas li kom nws cov zis tam sim no ripple me dua, yuav tsum muaj qhov tso zis me me, ua kom muaj txiaj ntsig zoo kom ua tiav lub zog siab ntawm lub voj voog.
Daim duab 1 Tso zis tam sim no Boost vs Buck
Cov hom kev tswj hwm ntawm LED tsav chips yog hom tam sim no (CM), COFT (tswj OFF-time), COFT & PCM (nruab nrab hom) hom.Piv nrog rau kev tswj hom tam sim no, COFT tswj hom tsis tas yuav tsum muaj lub voj voog nyiaj, uas yog qhov zoo rau kev txhim kho lub zog ceev, thaum muaj cov lus teb sai dua.
Tsis zoo li lwm hom kev tswj hwm, COFT tswj hom nti muaj qhov sib cais COFF tus pin rau kev teeb tsa lub sijhawm.Kab lus no qhia txog kev teeb tsa thiab kev ceev faj rau sab nraud ntawm COFF raws li COFT-tswj Buck LED tsav nti.
Basic configuration ntawm COFF thiab ceev faj
Txoj cai tswj hwm ntawm COFT hom yog tias thaum lub inductor tam sim no nce mus txog theem tam sim no, lub raj sab sauv tawm thiab lub raj qis dua.Thaum lub sij hawm tig-tawm mus txog tOFF, lub raj sab saud rov qab ua dua.Tom qab lub raj sab sauv kaw, nws yuav nyob twj ywm rau lub sijhawm tas mus li (tOFF).tOFF yog teem los ntawm lub capacitor (COFF) thiab tso zis voltage (Vo) ntawm lub periphery ntawm lub Circuit Court.Qhov no yog qhia nyob rau hauv daim duab 2. Vim hais tias lub ILED yog nruj me ntsis tswj, Vo yuav nyob twj ywm ze li ntawm ib tug ntau yam ntawm input voltages thiab kub, uas ua rau ib tug ze li ntawm tOFF, uas yuav xam tau siv Vo.
Daim duab 2. off time control circuit thiab tOFF xam mis
Nws yuav tsum tau muab sau tseg tias thaum xaiv dimming txoj kev los yog dimming Circuit Court yuav tsum tau ib tug luv luv tso zis, lub Circuit Court yuav tsis pib zoo nyob rau lub sij hawm no.Lub sij hawm no, lub inductor tam sim no ripple ua loj, cov zis voltage yuav tsawg heev, deb tsawg tshaj li qhov teeb voltage.Thaum qhov tsis ua haujlwm no tshwm sim, lub inductor tam sim no yuav ua haujlwm nrog lub sijhawm tawm ntau tshaj plaws.Feem ntau lub sijhawm tawm ntau tshaj plaws nyob rau hauv lub nti ncav cuag 200us ~ 300us.Lub sijhawm no lub inductor tam sim no thiab cov zis hluav taws xob zoo li nkag mus rau hom hiccup thiab tsis tuaj yeem tso tawm ib txwm.Daim duab 3 qhia txog qhov txawv txav ntawm qhov inductor tam sim no thiab cov zis hluav taws xob ntawm TPS92515-Q1 thaum lub shunt resistor siv rau lub load.
Daim duab 4 qhia peb hom kab hluav taws xob uas yuav ua rau cov teeb meem saum toj no.Thaum lub shunt FET yog siv rau dimming, lub shunt resistor yog xaiv rau lub load, thiab lub load yog ib tug LED switching matrix Circuit Court, tag nrho cov ntawm lawv yuav luv tawm qhov tso zis voltage thiab tiv thaiv ib txwm pib.
Daim duab 3 TPS92515-Q1 Inductor Tam sim no thiab cov zis hluav taws xob (Resistor Load Output Short Fault)
Daim duab 4. Circuit Court uas yuav ua rau cov zis tawm luv
Txhawm rau zam qhov no, txawm tias qhov tso zis luv luv, tseem xav tau qhov hluav taws xob ntxiv los them rau COFF.Cov khoom siv sib npaug uas VCC / VDD tuaj yeem siv tau raws li tus nqi COFF capacitors, tswj lub sijhawm ua haujlwm ruaj khov, thiab ua kom lub zog tas li.Cov neeg siv khoom tuaj yeem khaws cov resistor ROFF2 ntawm VCC / VDD thiab COFF thaum tsim lub voj voog, raws li qhia hauv daim duab 5, los pab txhawb kev debugging tom qab.Nyob rau tib lub sijhawm, TI daim ntawv teev cov ntaub ntawv feem ntau muab ROFF2 kev suav cov mis raws li lub hauv paus ntawm lub nti los pab txhawb cov neeg siv khoom xaiv ntawm resistor.
Daim duab 5. SHUNT FET Sab Nraud ROFF2 Txhim Kho Circuit Court
Ua qhov luv luv-circuit output txhaum ntawm TPS92515-Q1 hauv daim duab 3 ua piv txwv, txoj kev hloov kho hauv daim duab 5 yog siv los ntxiv ib qho ROFF2 ntawm VCC thiab COFF los them rau COFF.
Xaiv ROFF2 yog txheej txheem ob kauj ruam.Thawj kauj ruam yog xam lub sij hawm yuav tsum tau kaw (tOFF-Shunt) thaum lub shunt resistor yog siv rau cov zis, qhov twg VSHUNT yog cov zis voltage thaum lub shunt resistor yog siv rau lub load.
Cov kauj ruam thib ob yog siv tOFF-Shunt los xam ROFF2, uas yog tus nqi ntawm VCC rau COFF ntawm ROFF2, xam raws li hauv qab no.
Raws li kev suav, xaiv qhov tsim nyog ROFF2 tus nqi (50k Ohm) thiab txuas ROFF2 ntawm VCC thiab COFF nyob rau hauv qhov teeb meem txhaum cai hauv daim duab 3, thaum cov zis hluav taws xob zoo li qub.Kuj tseem nco ntsoov tias ROFF2 yuav tsum loj dua ROFF1;Yog tias nws qis dhau lawm, TPS92515-Q1 yuav ntsib teeb meem tsawg kawg ntawm lub sijhawm tig, uas yuav ua rau muaj kev nce ntxiv tam sim no thiab ua rau muaj kev puas tsuaj rau cov khoom siv nti.
Daim duab 6. TPS92515-Q1 inductor tam sim no thiab cov zis voltage (ib txwm tom qab ntxiv ROFF2)
Post lub sij hawm: Feb-15-2022