Intshayelelo yetshiphu yomqhubi we-LED
kunye nophuhliso olukhawulezayo lweshishini lombane weemoto, iitshiphusi zomqhubi we-LED ezinoxinzelelo oluphezulu olunoluhlu olubanzi lwamandla ombane zisetyenziswa ngokubanzi kukhanyiso lwemoto, kubandakanywa izibane zangaphandle nangasemva, izibane zangaphakathi kunye nokukhanyisa umva.
Iitshiphusi zomqhubi we-LED zinokwahlulwa zibe yi-analog dimming kunye ne-PWM dimming ngokwendlela yobumnyama.Ubumnyama be-analog bulula kakhulu, ubumnyama be-PWM buntsokothile, kodwa uluhlu lobumnyama bomgca likhulu kune-analog dimming.I-chip yomqhubi we-LED njengeklasi ye-chip yolawulo lwamandla, i-topology yayo ikakhulu i-Buck kunye ne-Boost.impundu sesekethe imveliso yangoku eqhubekayo ukuze imveliso yayo yangoku ripple lincinci, ifuna capacitance imveliso encinane, luncedo ngakumbi ukuphumeza uxinano lwamandla aphezulu kwisekethe.
Umzobo 1 Imveliso yangoku iBoost vs Buck
Iindlela zokulawula eziqhelekileyo ze-chips zomqhubi we-LED yimowudi yangoku (CM), i-COFT (i-controlled OFF-time) imowudi, i-COFT & PCM (imowudi ehamba phambili yangoku).Xa kuthelekiswa nolawulo lwemowudi yangoku, imo yokulawula i-COFT ayifuni imbuyekezo ye-loop, ehambelana nokuphucula ubuninzi bamandla, ngelixa unempendulo eguqukayo ngokukhawuleza.
Ngokungafaniyo nezinye iindlela zolawulo, imowudi yolawulo ye-COFT ine-pin eyahlukileyo ye-COFF yokusetha ixesha elingekhoyo.Eli nqaku lizisa ukucwangciswa kunye nezilumkiso zesekethe yangaphandle yeCOFF ngokusekelwe kwi-chip ye-Buck ye-LED yomqhubi we-COFT.
Ubumbeko olusisiseko lwe-COFF kunye nezilumkiso
Umgaqo wokulawula we-COFT imodi kukuba xa i-inductor yangoku ifikelela kwinqanaba elimiselweyo, ityhubhu ephezulu iyacima kwaye i-tube ephantsi ivula.Xa ixesha lokucima lifikelela kwi-tOFF, ityhubhu ephezulu ivula kwakhona.Emva kokuba ityhubhu ephezulu ivaliwe, iya kuhlala ivaliwe ixesha elingapheliyo (tOFF).I-tOFF isetwa yi-capacitor (COFF) kunye ne-voltage ephumayo (Vo) kwi-periphery yesiphaluka.Oku kuboniswe kuMfanekiso 2. Ngenxa yokuba i-ILED ilawulwa ngokuqinileyo, i-Vo iya kuhlala iphantse ihlale ihleli phezu koluhlu olubanzi lwee-voltages ze-input kunye namaqondo okushisa, okubangela ukuba i-tOFF iphantse rhoqo, ingabalwa ngokusebenzisa i-Vo.
Umzobo 2. isiphaluka solawulo lwexesha kunye nefomula yokubala ye-tOFF
Kufuneka kuqatshelwe ukuba xa indlela ekhethiweyo ye-dimming okanye i-dimming circuit idinga imveliso emfutshane, isiphaluka asiyi kuqalisa ngokufanelekileyo ngeli xesha.Ngeli xesha, i-ripple yangoku ye-inductor iba nkulu, amandla ombane aphumayo aphantsi kakhulu, angaphantsi kakhulu kunombane obekiweyo.Xa oku kungaphumeleli kusenzeka, i-inductor yangoku iya kusebenza kunye nexesha elide lokuphumla.Ngokuqhelekileyo ixesha eliphezulu lokuphumla elibekwe ngaphakathi kwe-chip lifikelela kwi-200us ~ 300us.Ngeli xesha i-inductor yangoku kunye ne-voltage ephumayo ibonakala ingena kwimodi ye-hiccup kwaye ayikwazi ukuvelisa ngokuqhelekileyo.Umzobo we-3 ubonisa i-waveform engaqhelekanga ye-inductor yangoku kunye ne-voltage yemveliso ye-TPS92515-Q1 xa i-shunt resistor isetyenziselwa umthwalo.
Umzobo we-4 ubonisa iintlobo ezintathu zeesekethe ezinokubangela iimpazamo ezingentla.Xa i-shunt FET isetyenziselwa ukufiphala, i-shunt resistor ikhethelwa umthwalo, kwaye umthwalo yisekethe ye-matrix yokutshintsha kwe-LED, zonke zinokumfutshane ngaphandle kombane wokukhupha kwaye zithintele ukuqala okuqhelekileyo.
Umzobo we-3 TPS92515-Q1 Inductor yangoku kunye ne-Output Voltage (I-Resistor Load Output Short Fault)
Umzobo 4. Iisekethe ezinokubangela iifutshane zemveliso
Ukuze ugweme oku, nangona isiphumo sifutshane, i-voltage eyongezelelweyo isafuneka ukuhlawulisa i-COFF.Ubonelelo oluhambelanayo ukuba i-VCC / VDD ingasetyenziselwa njengentlawulo ye-COFF capacitors, igcina ixesha elizinzile, kwaye igcina i-ripple rhoqo.Abathengi banokugcina i-resistor ROFF2 phakathi kwe-VCC / VDD kunye ne-COFF xa uyila isiphaluka, njengoko kuboniswe kuMzobo 5, ukuququzelela umsebenzi wokutshatyalaliswa kamva.Kwangaxeshanye, i-chip ye-TI yedatha ihlala inika i-ROFF2 ifomula yokubala ngokwe-circuit yangaphakathi ye-chip ukuququzelela ukhetho lomthengi lokumelana.
Umfanekiso 5. SHUNT FET ISekethe yoPhuculo lwe-ROFF2 yaNgaphandle
Ukuthatha i-short-circuit output error ye-TPS92515-Q1 kwi-Figure 3 njengomzekelo, indlela elungisiweyo kwi-Figure 5 isetyenziselwa ukongeza i-ROFF2 phakathi kwe-VCC kunye ne-COFF ukuhlawula i-COFF.
Ukukhetha i-ROFF2 yinkqubo enamanyathelo amabini.Isinyathelo sokuqala kukubala ixesha elifunekayo lokuvala (tOFF-Shunt) xa i-shunt resistor isetyenziselwa imveliso, apho i-VSHUNT yi-voltage ephumayo xa i-shunt resistor isetyenziselwa umthwalo.
Isinyathelo sesibini kukusebenzisa i-tOFF-Shunt ukubala i-ROFF2, eyintlawulo esuka kwi-VCC ukuya kwi-COFF nge-ROFF2, ibalwe ngolu hlobo lulandelayo.
Ngokusekelwe ekubaleni, khetha ixabiso elifanelekileyo le-ROFF2 (i-50k Ohm) kwaye udibanise i-ROFF2 phakathi kwe-VCC kunye ne-COFF kwimeko yephutha kwi-Figure 3, xa ukuphuma kwesiphaluka kuqhelekileyo.Kwakhona qaphela ukuba i-ROFF2 kufuneka ibe nkulu kakhulu kune-ROFF1;ukuba iphantsi kakhulu, i-TPS92515-Q1 iya kuba neengxaki ezincinci zokuvula ixesha, okuya kubangela ukwanda kwangoku kunye nomonakalo onokwenzeka kwisixhobo se-chip.
Umzobo 6. I-TPS92515-Q1 i-inductor yangoku kunye ne-voltage yemveliso (eqhelekileyo emva kokongeza i-ROFF2)
Ixesha lokuposa: Feb-15-2022