OnSemiNCP1380准谐振电流模式大功率离线电源方案.docx

On Semi NCP1380准谐振电流模式大功率离线电源方案关键词：电源管理,AC/DC转换器,离线电源On Semi 公司的NCP1380是大功率通用离线电源用的准谐振电流模式控制器,谷底开关工作,轻负载时频率回馈以提高效率, 峰值电流源/沉为+500mA/-800mA, 无负载的待机功耗极低,适用于TV,STB的大功率AC/DC转换器,笔记本电脑的离线适配器.本文介绍NCP1380主要特性,内部电路架构, 谷底检测电路, 过载检测电路, 过压/超温检测电路以及典型应用电路.Quasi-Resonant Current-Mode Controller for High-Power Universal Off-Line SuppliesThe NCP1380 hosts a highperformance circuitry aimed to powering quasiresonant converters. Capitalizing on a proprietary valleylockout system, the controller shifts gears and reduces the switching frequency as the power loading becomes lighter. This results in a stable operation despite switching events always occurring in the drainsource valley. This system works down to the 4th valley and toggles to a variable frequency mode beyond, ensuring an excellent standby power performance.To improve the safety in overload situations, the controller includes an Over Power Protection (OPP) circuit which clamps the delivered power at highline. Safetywise, a fixed internal timer relies on the feedback voltage to detect a fault. Once the timer elapses, the controller stops and stays latched for option A and C or enters autorecovery mode for option B and D.Particularly well suited for adapter applications, the controller features a pin to implement either a combined overvoltage / overtemperature protection (Version A and B) or a combined brownout/overvoltage protection (Version C and D).NCP1380主要特性: QuasiResonant Peak CurrentMode Control Operation Valley Switching Operation with ValleyLockout for NoiseImmune Operation Frequency Foldback at Light Load to Improve the Light Load Efficiency Adjustable Over Power Protection AutoRecovery or Latched Internal Output ShortCircuit Protection Fixed Internal 80 ms Timer for ShortCircuit Protection Combined Overvoltage and Overtemperature Protection (A and B Versions) Combined Overvoltage Protection and BrownOut (C and D Versions) +500mA/800 mA Peak Current Source/Sink Capability Internal Temperature Shutdown Direct Optocoupler Connection Extended VCC Range Operation Up to 28 V Extremely Low NoLoad Standby Power SO8 Package These Devices are PbFree and are RoHS CompliantNCP1380应用: High Power acdc Converters for TVs, SetTop Boxes etc. Offline Adapters for Notebooks图1.NCP1380内部电路架构:A型和B型图2.NCP1380内部电路架构:C型和D型图3.谷底检测电路图4.过载检测电路图5.超功率补偿电路图6.过压/超温检测电路(A型和B