NCP1271 19V，3.0A通用AC－DC适配器设计方案,NCP1271 DESIGN

NCP1271 19V，3.0A通用AC－DC适配器设计方案,NCP1271 DESIGN

关键字：NCP1271,开关电源电路图

OnSemi公司的NCP1271是一款最新的固定频率电流模式PWM开关控制器，具有为低级声频噪声提供可调节的Soft-Skip待机操作模式，为节省待机功耗内部集成高压启动，过载故障检测定时器，内部锁保护功能特性。本文首先介绍NCP1271、基本特性、内部框图及应用领域，并给出相应设计方案的设计原理图、元器件列表及PCB元件布局图。
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应用领域：
•AC−DCAdaptersforNotebooks,LCDMonitors
•OfflineBatteryChargers
•ConsumerElectronicAppliancesSTB,DVD,DVDR

图1.NCP1271内部方框图

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

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

consumptionis83mWat230Vacandthelightloadoperationisgreaterthan75%efficient.

NCP1271ADAPGEVB方案原理图：

图2.NCP1271ADAPGEVB方案原理图

NCP1271ADAPGEVB方案材料清单：


PCB元件布局图：



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