Isingeniso se-chip yomshayeli we-LED
ngokuthuthuka okusheshayo kwemboni yezogesi zezimoto, ama-chips omshayeli we-LED anomthamo omkhulu we-voltage ebanzi asetshenziswa kabanzi ekukhanyisweni kwezimoto, okuhlanganisa ukukhanya kwangaphandle nangemuva, ukukhanya kwangaphakathi nokukhanyisa ngemuva.
Ama-chips omshayeli we-LED angahlukaniswa abe yi-analog dimming kanye ne-PWM dimming ngokuya ngendlela yokufiphala.Ukufiphalisa kwe-analogi kulula uma kuqhathaniswa, ukufiphalisa kwe-PWM kuyinkimbinkimbi, kodwa ububanzi bokufiphalisa ngomugqa bukhulu kunokufiphala kwe-analog.I-chip yomshayeli we-LED njengesigaba se-chip yokuphatha amandla, i-topology yayo ikakhulukazi i-Buck ne-Boost.i-buck circuit okukhiphayo okwamanje okuqhubekayo ukuze i-ripple yayo yamanje ephumayo ibe yincane, idinga amandla amancane okukhiphayo, okulungele ukufeza ukuminyana kwamandla aphezulu wesekethe.
Umfanekiso 1 Okukhiphayo Ukukhuthaza Kwamanje vs Buck
Izindlela zokulawula ezivamile zama-chips abashayeli be-LED imodi yamanje (CM), imodi ye-COFT (i-OFF-time elawulwayo), imodi ye-COFT ne-PCM (imodi yamanje ephezulu).Uma kuqhathaniswa nokulawula imodi yamanje, imodi yokulawula ye-COFT ayidingi isinxephezelo se-loop, esiza ekuthuthukiseni ukuminyana kwamandla, kuyilapho kunempendulo esheshayo eguqukayo.
Ngokungafani nezinye izindlela zokulawula, i-chip yemodi yokulawula ye-COFT inephinikhodi ehlukile ye-COFF yokusetha isikhathi esingekho.Lesi sihloko sethula ukucushwa nezinyathelo zokuphepha zomjikelezo wangaphandle we-COFF ngokusekelwe ku-chip yomshayeli we-Buck LED evamile elawulwa yi-COFT.
Ukucushwa okuyisisekelo kwe-COFF nezinyathelo zokuphepha
Isimiso sokulawula semodi ye-COFT siwukuthi lapho i-inductor yamanje ifinyelela ezingeni elimisiwe lamanje, ishubhu eliphezulu liyacisha futhi ishubhu engezansi iyavula.Uma isikhathi sokuvala sifika ku-tOFF, ishubhu eliphezulu liyavula futhi.Ngemuva kokuthi ishubhu engenhla icishiwe, izohlala ivaliwe isikhathi esingaguquki (tOFF).I-tOFF isethwe yi-capacitor (COFF) kanye ne-voltage ephumayo (Vo) endaweni ezungezile yesekethe.Lokhu kuboniswa kuMfanekiso 2. Ngenxa yokuthi i-ILED ilawulwa ngokuqinile, i-Vo izohlala icishe ibe njalo ezinhlobonhlobo zama-voltage okufakwayo namazinga okushisa, okuholela ku-tOFF ecishe ibe njalo, engabalwa kusetshenziswa i-Vo.
Umfanekiso 2. Isekhethi yokulawula isikhathi kanye nefomula yokubala ye-tOFF
Kumele kuqashelwe ukuthi lapho indlela ekhethiwe yokufiphalisa noma isifunda sokufiphalisa idinga okukhiphayo okufushane, isifunda ngeke siqale kahle ngalesi sikhathi.Ngalesi sikhathi, i-ripple yamanje ye-inductor iba nkulu, i-voltage ephumayo iba phansi kakhulu, ingaphansi kakhulu kune-voltage ebekiwe.Uma lokhu kwehluleka kwenzeka, i-inductor yamanje izosebenza nesikhathi esiphezulu sokuphumula.Ngokuvamile isikhathi esiphezulu sokuphumula esibekwe ngaphakathi kwe-chip sifinyelela ku-200us ~ 300us.Ngalesi sikhathi i-inductor yamanje kanye ne-voltage ephumayo ibonakala ingena kumodi ye-hiccup futhi ayikwazi ukukhipha ngokujwayelekile.Umfanekiso wesi-3 ubonisa i-waveform engavamile ye-inductor yamanje kanye ne-voltage ephumayo ye-TPS92515-Q1 lapho i-shunt resistor isetshenziselwa umthwalo.
Umfanekiso 4 ukhombisa izinhlobo ezintathu zamasekhethi ezingadala amaphutha angenhla.Lapho i-shunt FET isetshenziselwa ukufiphalisa, i-shunt resistor ikhethelwa ukulayisha, futhi umthwalo uyisekethe ye-matrix yokushintsha i-LED, wonke angase abe mfushane ku-voltage okukhiphayo futhi avimbele ukuqala okuvamile.
Umfanekiso 3 TPS92515-Q1 Inductor Yamanje kanye Nogesi Ophumayo (Iphutha Elifushane Lokukhipha Okumelene Nomthwalo)
Umfanekiso 4. Amasekhethi angabangela izikhindi eziphumayo
Ukuze ugweme lokhu, ngisho nalapho okukhiphayo kufushane, i-voltage eyengeziwe isadingeka ukushaja i-COFF.Ukunikezwa okuhambisanayo i-VCC/VDD engasetshenziswa njengokushaja ama-capacitor e-COFF, igcina isikhathi sokuphumula esizinzile, futhi igcina ukugeleza okuqhubekayo.Amakhasimende angagcina i-resistor ROFF2 phakathi kwe-VCC/VDD ne-COFF lapho eklama isekethe, njengoba kuboniswe kuMfanekiso 5, ukuze kube lula umsebenzi wokususa iphutha kamuva.Ngesikhathi esifanayo, idatha yedatha yechip ye-TI ngokuvamile inikeza ifomula yokubala ethize ye-ROFF2 ngokuya ngomjikelezo wangaphakathi we-chip ukuze kube lula ukukhetha kwekhasimende kokumelana.
Umfanekiso 5. I-SHUNT FET Yangaphandle Yesekethe Yokuthuthukisa I-ROFF2
Ukuthatha iphutha lokukhipha i-short-circuit ye-TPS92515-Q1 ku-Figure 3 njengesibonelo, indlela eguquliwe ku-Figure 5 isetshenziselwa ukwengeza i-ROFF2 phakathi kwe-VCC ne-COFF ukuze kukhokhiswe i-COFF.
Ukukhetha i-ROFF2 kuyisinyathelo esinezinyathelo ezimbili.Isinyathelo sokuqala ukubala isikhathi esidingekayo sokuvala (tOFF-Shunt) lapho i-shunt resistor isetshenziselwa okukhiphayo, lapho i-VSHUNT iyi-voltage yokuphuma lapho i-shunt resistor isetshenziselwa umthwalo.
Isinyathelo sesibili siwukusebenzisa i-tOFF-Shunt ukubala i-ROFF2, okuyinkokhiso esuka ku-VCC iye ku-COFF nge-ROFF2, ebalwa ngale ndlela elandelayo.
Ngokusekelwe esibalweni, khetha inani elifanele le-ROFF2 (50k Ohm) bese uxhuma i-ROFF2 phakathi kwe-VCC ne-COFF endaweni enephutha kuMfanekiso 3, lapho ukuphuma kwesekethe kuyinto evamile.Futhi qaphela ukuthi i-ROFF2 kufanele ibe nkulu kakhulu kune-ROFF1;uma iphansi kakhulu, i-TPS92515-Q1 izobhekana nezinkinga ezincane zokuvula isikhathi, okuzophumela ekwenyukeni komonakalo wamanje kanye okungenzeka kudivayisi ye-chip.
Umfanekiso 6. TPS92515-Q1 inductor yamanje kanye ne-voltage ephumayo (evamile ngemva kokwengeza i-ROFF2)
Isikhathi sokuthumela: Feb-15-2022