NCP1271 19V，3.0A通用AC－DC適配器設計方案,NCP1271 DESIGN

關鍵字：NCP1271,開關電源電路圖

OnSemi公司的NCP1271是一款最新的固定頻率電流模式PWM開關控制器，具有為低級聲頻噪聲提供可調節(jié)的Soft-Skip待機操作模式，為節(jié)省待機功耗內部集成高壓啟動，過載故障檢測定時器，內部鎖保護功能特性。本文首先介紹NCP1271、基本特性、內部框圖及應用領域，并給出相應設計方案的設計原理圖、元器件列表及PCB元件布局圖。
TheNCP1271representsanew,pintopincompatible,generationofthesuccessful7?pincurrentmodeNCP12XXproductseries.

ThecontrollerallowsforexcellentstandbypowerconsumptionbyuseofitsadjustableSoft?Skipmodeandintegratedhighvoltagestartup
FET.ThisproprietarySoft?Skipalsodramaticallyreducestheriskofacousticnoise.Thisallowstheuseofinexpensivetransformersand

capacitorsintheclampingnetwork.Internalfrequencyjittering,rampcompensation,timer?basedfaultdetectionandalatchinputmake

thiscontrolleranexcellentcandidateforconverterswhereruggednessandcomponentcostarethekeyconstraints.

NCP1271主要特性：
?Fixed?FrequencyCurrent?ModeOperationwithRampCompensationandSkipCycleinStandbyCondition
?Timer?BasedFaultProtectionforImprovedOverloadDetection
?“Soft?SkipMode”TechniqueforOptimalNoiseControlinStandby
?InternalHigh?VoltageStartupCurrentSourceforLosslessStartup
?_5%CurrentLimitAccuracyovertheFullTemperatureRange
?AdjustableSkipLevel
?InternalLatchforEasyImplementationofOvervoltageandOvertemperatureProtection
?FrequencyJitteringforSoftenedEMISignature
?+500mA/?800mAPeakCurrentDriveCapability
?Sub?100mWStandbyPowercanbeAchieved
?Pin?to?PinCompatiblewiththeExistingNCP120XSeries
?ThisisaPb?FreeDevice

NCP1271應用領域：
?AC?DCAdaptersforNotebooks,LCDMonitors
?OfflineBatteryChargers
?ConsumerElectronicAppliancesSTB,DVD,DVDR

圖1.NCP1271內部方框圖

NCP1271ADAPGEVB方案介紹：
Thisevaluationboarduser’smanualpresentsanexamplecircuitusingtheNCP1271(65kHzversion)inaflybacktopology.

Thedesignstepsandsubsequentmeasurementsarealsoincluded.AnExcelbaseddesignworksheetisavailableatwww.onsemi.com.
Themeasurementsshowthatthe19V,3.0Acircuitdeliversabove85%acrossauniversalinput(85to265Vac).Thenoloadstandby

consumptionis83mWat230Vacandthelightloadoperationisgreaterthan75%efficient.

NCP1271ADAPGEVB方案原理圖：

圖2.NCP1271ADAPGEVB方案原理圖

NCP1271ADAPGEVB方案材料清單：


PCB元件布局圖：



TopView


BottomView