 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
HT7L4815 Datasheet(PDF) 6 Page - Holtek Semiconductor Inc |
|
||||||||||||||||||||||||||||||
HT7L4815 Datasheet(HTML) 6 Page - Holtek Semiconductor Inc |
|
|
6 / 9 page  Rev. 1.00 6 June 26, 2015 HT7L4815 Preliminary Constant Current Control The HT7L4815 will sense the overall inductor currentandformaclosed-loopwithaninternalerror amplifiertoobtainhighconstantcurrentaccuracy. TheCSvoltageandthe0.2Vreferencevoltageform theinputstoaninternalGmamplifierwhoseoutput isintegratedviaanexternalCOMPcapacitor.The ONtimeoftheMOSFETiscontrolledbytheCOMP voltagetoadjusttheoutputcurrent. LEB on CS – Leading-Edge Blanking EachtimetheinternalpowerMOSFETisswitched on,aturn-onspikewillinevitablyoccuratthesense resistor.Toavoidfaultytriggering,a400nsleading- edgeblanktimeisgenerated.Asthisfunctionis provided conventional RC filtering is therefore unnecessary.Duringthisblankingperiod,thecurrent- limitcomparatorisdisabledandcanthereforenot switchoffthegatedriver. OVP on VCC – Over Voltage Protection InordertopreventPWMcontrollerdamage,the deviceincludesanOVPfunctiononVCC.Should theVCCvoltagebehigherthantheOVPthreshold voltage of 29V, the PWM controller will stop operating immediately.When theVCC voltage decreasesbelowtheUVLOofflevel,thecontroller willreset. LED Open Protection – ZCD OVP The LED voltage is reflected on the ZCD pin througharesistorRZCD.Whenthecurrentonthe resistorRZCDishigherthan300μA,thenZCDOVP protectionwilltakeplace.HerethePWMcontroller willstopoperatingimmediately.WhentheVCC voltagedecreasesbelowtheUVLOofflevel,the controllerwillreset. VOVP-ZCDcanbesetusingthefollowingequation: VOVP-ZCD=VZCDH+IOVP×RZCD VZCDHisthe3VupperclampvoltageontheZCD pin.IOVPrepresentstheOVPcurrentlevelontheZCD pinwhichis300μA.RZCDstandsfortheresistorcon- nectedbetweentheZCDpinandtheLEDpositive terminal. OCP – Over Current Protection The device includes an over current protection functionontheCSpin.Aninternalcircuitdetectsthe currentlevelandwhenthecurrentislargerthanthe overcurrentprotectionthresholdlevel,VOCP/RCS,the gateoutputwillremainatalowlevel. LED Short Protection – SCP TheoutputvoltagedropswhenanumberofLEDs inastringareshortedresultinginavoltagedropat VCC.OncetheVCCdropsbelow10V,thedevice willstopoperating.Undersuchsituations,thestart-up operationwillrechargetheVCCpinthroughthestart- upresistorandthedevicewillentertheUVLOhiccup mode. Thermal Protection Athermalprotectionfeatureisincludedtoprotect thedevicefromexcessiveheatdamage.Whenthe junctiontemperatureexceedsathresholdof150°C, thethermalprotectionfunctionwillturnoffthe DRAIN terminal immediately. When the VCC decreasesbelowtheUVLOofflevel,thecontroller willreset. |
Similar Part No. - HT7L4815 |
|
Similar Description - HT7L4815 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.NET |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
