LED mutyairi chip sumo
Nekukurumidza kusimudzira kweindasitiri yemagetsi emotokari, machipisi emutyairi emutyairi epamusoro-soro ane hupamhi hwemagetsi emagetsi anoshandiswa zvakanyanya mukuvhenekesa mota, kusanganisira mwenje wekunze nekumashure, mwenje wemukati uye kuratidza kumashure.
LED mutyairi machipisi anogona kukamurwa kuita analog dimming uye PWM dimming zvinoenderana ne dimming nzira.Analog dimming iri nyore, PWM dimming haina kuoma, asi mutsara dimming renji yakakura kupfuura analog dimming.LED mutyairi chip sekirasi yesimba manejimendi chip, yayo topology kunyanya Buck uye Boost.buck redunhu goho ikozvino inoenderera kuitira kuti goho rayo razvino ripple ridiki, rinoda diki goho capacitance, inogoneka kuti iwane yakakwirira simba density yedunhu.
Mufananidzo 1 Output Current Boost vs Buck
Iwo akajairwa kudzora modhi ye LED mutyairi machipisi ari azvino modhi (CM), COFT (inodzorwa OFF-nguva) modhi, COFT & PCM (peak ikozvino modhi) maitiro.Kuenzaniswa neazvino maitiro ekutonga, COFT yekudzora modhi haidi muripo we loop, iyo inobatsira kuvandudza simba density, uku uine inokurumidza kukurumidza mhinduro.
Kusiyana nemamwe mamodhi ekudzora, iyo COFT yekudzora modhi chip ine yakaparadzana COFF pini yekusa-nguva kuseta.Ichi chinyorwa chinosuma magadzirirwo uye ekudzivirira kwedunhu rekunze reCOFF zvichibva pane yakajairwa COFT-inodzorwa Buck LED driver chip.
Kugadziriswa kwekutanga kweCOFF uye zvidziviriro
Iyo yekudzora musimboti weCOFT modhi ndeyekuti kana inductor yazvino ichisvika padanho razvino, chubhu yekumusoro inodzima uye chubhu yepasi inobatidzwa.Kana nguva yekudzima yasvika tOFF, iyo yekumusoro chubhu inovhura zvakare.Mushure mekunge chubhu yekumusoro ichidzima, icharamba yakadzimwa kwenguva isingaperi (tOFF).tOFF yakaiswa ne capacitor (COFF) uye inobuda voltage (Vo) panharaunda yedunhu.Izvi zvinoratidzwa muMufananidzo 2. Nemhaka yokuti ILED yakanyatsogadziriswa, Vo icharamba iine nguva yakawanda pamusoro pehuwandu hwemagetsi ekupinza uye kupisa, zvichiita kuti tOFF igare, iyo inogona kuverengwa uchishandisa Vo.
Mufananidzo 2. kure kure nguva yekudzora dunhu uye tOFF calculation formula
Izvo zvinofanirwa kucherechedzwa kuti kana yakasarudzwa dimming nzira kana dimming reketi inoda kupfupika kuburitsa, dunhu harizotanga zvakanaka panguva ino.Panguva ino, iyo inductor yazvino ripple inova yakakura, iyo inobuda voltage inova yakaderera kwazvo, ishoma pane yakatarwa voltage.Kana kukundikana uku kuchiitika, inductor yazvino ichashanda pamwe neakanyanya kureba nguva.Kazhinji iyo yakanyanya kuremerwa nguva yakaiswa mukati chip inosvika 200us ~ 300us.Panguva ino inductor yazvino uye inobuda voltage inoita kunge inopinda muiyo hiccup mode uye haigone kubuda zvakajairika.Mufananidzo 3 unoratidza iyo isina kujairika waveform yeinductor yazvino uye inobuda voltage yeTPS92515-Q1 kana shunt resistor ichishandiswa pamutoro.
Mufananidzo 4 unoratidza marudzi matatu emaseketi anogona kukonzera kukanganisa kuri pamusoro.Kana iyo shunt FET ichishandiswa kudzima, shunt resistor inosarudzirwa mutoro, uye mutoro ndeye LED switching matrix wedunhu, ese anogona kupfupisa kubuda kwemagetsi uye kudzivirira yakajairika kutanga-up.
Mufananidzo 3 TPS92515-Q1 Inductor Yazvino uye Inobuda Voltage (Resistor Load Output Short Fault)
Mufananidzo 4. Masekete anogona kukonzera kubuda shorts
Kuti udzivise izvi, kunyangwe kana iyo yakabuda ipfupi, imwezve voltage ichiri kudikanwa kubhadharisa COFF.Iyo yakafanana inopa iyo VCC / VDD inogona kushandiswa sekubhadhara iyo COFF capacitors, inochengetedza nguva yakagadzikana, uye inochengeta ripple nguva dzose.Vatengi vanogona kuchengetedza resistor ROFF2 pakati peVCC/VDD neCOFF pavanenge vachigadzira dunhu, sezvakaratidzwa muMufananidzo 5, kufambisa basa rekugadzirisa gare gare.Panguva imwecheteyo, iyo TI chip dhatabheti inowanzopa iyo chaiyo ROFF2 yekuverenga formula zvinoenderana neyemukati wedunhu chip kufambisa sarudzo yemutengi yekupikisa.
Mufananidzo 5. SHUNT FET External ROFF2 Improvement Circuit
Kutora kukanganisa kwekapfupi-pfupi yeTPS92515-Q1 muMufananidzo 3 semuenzaniso, nzira yakagadziridzwa muMufananidzo 5 inoshandiswa kuwedzera ROFF2 pakati peVCC neCOFF kubhadharisa COFF.
Kusarudza ROFF2 inhanho mbiri.Nhanho yekutanga ndeyekuverenga nguva inodiwa yekuvhara (tOFF-Shunt) apo shunt resistor inoshandiswa pakubuda, apo VSHUNT ndiyo inobuda magetsi apo shunt resistor inoshandiswa kumutoro.
Nhanho yechipiri ndeye kushandisa tOFF-Shunt kuverenga ROFF2, inova mutero kubva kuVCC kuenda kuCOFF kuburikidza neROFF2, yakaverengerwa seizvi.
Kubva pakuverenga, sarudza iyo yakakodzera ROFF2 kukosha (50k Ohm) uye batanidza ROFF2 pakati peVCC neCOFF mumhosva yemhosva muMufananidzo 3, kana kubudiswa kwedunhu kwakajairika.Uyewo cherechedza kuti ROFF2 inofanira kuva yakakura kudarika ROFF1;kana yakanyanya kuderera, iyo TPS92515-Q1 ichasangana nediki-nguva-yenguva matambudziko, izvo zvinozokonzera kuwedzera kwazvino uye kukuvara kunogoneka kune chip mudziyo.
Mufananidzo 6. TPS92515-Q1 inductor ikozvino uye kubuda kwemhepo (yakajairika mushure mekuwedzera ROFF2)
Nguva yekutumira: Feb-15-2022