LED tsim, rau lub ripple, theoretically thiab nyob rau hauv qhov tseeb yog tej yam kom tshwm sim. Nws muaj tsib txoj hauv kev los txo lossis txo nws lub zog:
Tsawg inductance thiab tso zis hluav taws xob lim
Raws li qhov formula ntawm LED tsav fais fab mov, qhov ntau ntawm qhov tam sim no fluctuation nyob rau hauv lub inductor inversely proportional rau cov nqi inductance, thiab cov zis tawm ripple yog inversely proportional rau cov zis capacitance. Yog li ua tus inductance tus nqi thiab qhov tawm ntawm tus nqi peev txheej yuav txo tau qhov ripple.
Tso zis zis thiab qhov tso tawm ntawm kev sib raug zoo: vripple = Imax / (Co × f). Nws tuaj yeem pom tau hais tias nce lub peev xwm tsim tawm tau txo qhov ripple.
Kev xyaum li ib txwm siv rau qhov tso zis hluav taws xob, siv cov khoom siv hluav taws xob los ntawm lub tshuab ua kom tau lub peev xwm ua tiav. Tab sis cov kua hluav taws xob hauv lub tshuab hluav taws xob tua hluav taws xob tsis zoo heev, thiab ESR loj kuj, yog li ntawd nws yuav tsum nyob rau hauv nrog lub ceramic capacitor, kom ua rau cov tsis muaj cov khoom siv hluav taws xob uas tsis muaj poom.
Tib lub sijhawm, LED tsav fais fab mov ua hauj lwm, qhov input voltage Vin unchanged, tab sis tam sim no nrog rau kev hloov pauv. Lub sijhawm no lub hwj huam tawm tswv yim tsis muab zoo tam sim no, feem ntau nyob ze cov tswv yim tam sim no (BucK hom, piv txwv li, SWITCH nyob ze), tus neeg muab lub sijhawm ua haujlwm rau tam sim no.
Secondary filter, uas yog, ntxiv rau LC lim
LC lim ntawm lub suab nrov ripple hluav nyhuv yog pom tseeb, raws li qhov kev tshem tawm ntawm cov zaus nquag mus xaiv qhov tsim nyog inductance capacitance lim Circuit Court, feem ntau yuav txo tau lub ripple. Txawm li cas los xij, hauv qhov no nws yog qhov tsim nyog los xav txog qhov piv txwv ntawm qhov sib piv ntawm qhov sib piv ntawm cov tswv yim sib piv.
Kev kuaj ua tiav ua ntej LC lim (Pa), thiab tso tawm qhov hluav taws xob tawm. Vim hais tias muaj inductor muaj DC tsis kam, thaum muaj tam sim no cov zis, yuav muaj ib qho kev poob qis ntawm qhov inductor, ua rau txo hwj chim tso zis hluav taws xob. Thiab qhov teeb meem no voltage yog nrog cov zis hloov tam sim no.
LED drive zog tso zis, ces LDO lim
Qhov no yog txoj kev zoo tshaj plaws los txo kev sib tw thiab suab nrov, qhov tawm qhov hluav taws xob yog qhov tsis tas li, tsis tas yuav hloov lub tswv yim qub, tab sis kuj yog tus nqi siab tshaj plaws, siab tshaj plaws kev noj kev haus. Cov LDO muaj qhov taw qhia: suab nrov suab.
Tom qab LDO, qhov ripple feem ntau qis dua 10mV.
Hauv daim diode thiab cov ciam teb rau C lossis RC
Thaum lub diode tawm ntawm kev kub ceev, xav txog kev tsis haum. Thaum diode rov qab rov qab, qhov sib npaug qhov sib npaug thiab qhov sib npaug ntawm qhov sib txawv ua rau RC oscillator uas ua rau cov oscillations siab. Yuav kom txo tau qhov kev ua kom qhov teeb meem loj no, lub diode yuav tsum tau txuas rau ob hnub ntawm lub capacitor C lossis RC tsis sib koom tes. Kev tswj feem ntau yog siv 10 Ω -100 Ω , lub capacitor siv 4.7pf-2.2nf.
Hauv daim diode ua tibzoo nrog lub peev xwm C lossis RC, qhov nqi ntawm qhov kev xeem rov los txiav txim siab. Yog tias tsis tsim nyog xaiv, tab sis yuav ua rau oscillation loj dua.
Diode tom qab induction inductance (EMI lim)
Qhov no kuj tseem siv tau los ua kom nrov suab nrov nrov. Rau zaus ntawm lub suab nrov nrov, xaiv qhov tsim nyog cov khoom ntim uas tsim nyog, zoo li qub tuaj yeem ua kom lub suab nrov. Nws yuav tsum raug sau tseg tias cov nqi ntawm qhov cim ntawm lub inductor no tau raws li cov kev cai tiag tiag.
Txoj kev xaus
Qhov saum toj no yog nyob rau ntawm tus qauv tsim, txo qhov tso zis tawm ntawm qee txoj kev, txawm tias tsis tag nro, tab sis daim ntawv thov yog txaus. Ntawm lub suab nrov, qhov tseeb tsis yog tas txhua daim ntaub ntawv, nws yog ib qho tseem ceeb raws li lawv cov qauv tsim, xws li cov khoom loj, tus nqi, qhov kev voj voog, xaiv txoj kev tsim nyog.
Kub khoom : L ED Street teeb , LED vaj huam sib luag , DLC LED Cog vaj huam sib luag teeb , LED mimming teeb , LED chaw teeb chaw teeb
