 |
数据搜索系统，热门电子元器件搜索 |
|
|
数据搜索系统，热门电子元器件搜索 |
|
SP7661 数据表(PDF) 9 Page - Sipex Corporation |
|
|
|||||||||||||||||||||||||||||
SP7661 数据表(HTML) 9 Page - Sipex Corporation |
|
|
9 / 20 page  9 Nov3-06 Rev I SP766 Wide Input Voltage Range 3A, 600kHz Buck Regulator © 2006 Sipex Corporation Error Amplifier and Voltage Loop TheheartoftheSP7661voltageerrorloop is a high performance, wide bandwidth transconductance amplifier. Because of theamplifier’scurrentlimited(+/-150µA) transconductance,therearemanywaysto compensatethevoltagelooportocontrolthe COMPpinexternally.Ifasimple,single-pole, single-zeroresponseisdesired,thencom- pensationcanbeassimpleasanRCcircuit toGround.Ifamorecomplexcompensation isrequired,thentheamplifierhasenough bandwidth(45°at4MHz),andenoughgain (60dB)torunTypeIIIcompensationschemes withadequategainandphasemarginsat crossoverfrequenciesgreaterthan50kHz. Thecommonmodeoutputoftheerroram- plifieris0.9Vto2.2V.Therefore,thePWM voltageramphasbeensetbetween1.1Vand 2.2Vtoensureproper0%to100%dutycycle capability. The voltage loop also includes twootherveryimportantfeatures.Oneisa nonsynchronousstartupmode.Basically,the synchronousrectifiercannotturnonunless thehighsideswitchhasattemptedtoturn onortheSSpinhasexceeded1.7V.This featurepreventsthecontrollerfrom“dragging down”theoutputvoltageduringstartupor infaultmodes. GH Voltage GL Voltage V(VIN) 0V -0V -V(Diode) V V(VIN)+V(VCC) BST Voltage V(VCC) TIME SWN Voltage VBST VSWN V(VCC) Thesecondfeatureisa100%dutycycle timeoutthatensuressynchronizedrefresh- ingoftheBSTcapacitoratveryhighduty ratios.IntheeventthatthehighsideNFET isonfor20continuousclockcycles,areset isgiventothePWMflipflophalfwaythrough the21stcycle.ThisforcesGLtoriseforthe cycle,inturnrefreshingtheBSTcapacitor. Theboostcapacitorisusedtogeneratea highvoltagedrivesupplyforthehighside switch,whichisVccaboveViN. Power MOSFETs TheSP7661containsapairofintegratedlow resistanceN-channelswitchesdesignedto driveupto3Aofoutputcurrent.Careshould betakentode-ratetheoutputcurrentbased onthethermalconditionsinthesystemsuch as ambient temperature, airflow and heat sinking.Maximumoutputcurrentcouldbe limitedbythermallimitationsofaparticular applicationbytakingadvantageoftheinte- grated-over-temperatureprotectivescheme employedintheSP7661.TheSP7661incor- poratesabuilt-inovertemperature protection topreventinternaloverheating. Setting Output Voltages TheSP7661canbesettodifferentoutput voltages.Therelationshipinthefollowing formulaisbasedonavoltagedividerfrom theoutputtothefeedbackpinVfB,whichis settoaninternalreferencevoltageof0.80V. Standard1%metalfilmresistorsofsurface mountsize0603arerecommended. VOut=0.80V [R1/R2+1] => R2=R1/ [ (VOut/0.80V)–1] WhereR1=10KΩandforVOut=0.80V setting,simplyremoveR2fromtheboard. Furthermore,onecouldselectthevalueof theR1andR2combinationtomeettheexact outputvoltagesettingbyrestrictingtheR1 resistance range such that 10KΩ < R1 < 100KΩforoverallsystemloopstability. APPLICATIONS INFORMATION |
|
|
链接网址 |
| ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 数据表链接 | 链接交换 | 制造商名单 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 |
Chinese ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
