安森美案例：NCP1380准谐振电流模式大功率离线电源方案

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 Supplies

The NCP1380 hosts a high−performance circuitry aimed to powering quasi−resonant converters. Capitalizing on a proprietary valley−lockout 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 drain−source 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 high−line. Safety−wise, 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 auto−recovery 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 brown−out/overvoltage protection (Version C and D).

NCP1380主要特性:

• Quasi−Resonant Peak Current−Mode Control Operation

• Valley Switching Operation with Valley−Lockout for Noise−Immune Operation

• Frequency Foldback at Light Load to Improve the Light Load Efficiency

• Adjustable Over Power Protection

• Auto−Recovery or Latched Internal Output Short−Circuit Protection

• Fixed Internal 80 ms Timer for Short−Circuit Protection

• Combined Overvoltage and Overtemperature Protection (A and B Versions)

• Combined Overvoltage Protection and Brown−Out (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 No−Load Standby Power

• SO−8 Package

• These Devices are Pb−Free and are RoHS Compliant

NCP1380应用:

• High Power ac−dc Converters for TVs, Set−Top 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型)

图7.过压/超温检测电路(C型和D型)

图8.典型应用电路(A型和B型)

图9.典型应用电路(C型和D型)

详情请见:

https://www.onsemi.cn/pub_link/Collateral/NCP1380-D.PDF