NCP1351数据手册集成电路（IC）的ACDC转换器离线开关规格书PDF

描述 Description

The NCP1351 is a current mode controller targeting low power off line flyback Switched Mode Power Supplies (SMPS) where cost is of utmost importance. Based on a fixed peak current technique (quasi fixed TON), the controller decreases its switching frequency as the load becomes lighter. As a result, a power supply using the NCP1351 naturally offers excellent no load power consumption, while optimizing the efficiency in other loading conditions. When the frequency decreases, the peak current is gradually reduced down to approximately 30% of the maximum peak current to prevent transformer mechanical resonance. The risk of acoustic noise is thus greatly diminished while keeping good standby power performance.An externally adjustable timer permanently monitors the feedback activity and protects the supply in presence of a short circuit or an overload. Once the timer elapses, NCP1351 stops switching and stays latched for version A, and tries to restart for Version B.The internal structure features an optimized arrangement which allows one of the lowest available startup current, a fundamental parameter when designing low standby power supplies. The negative current sensing technique minimizes the impact of the switching noise on the controller operation and offers the user to select the maximum peak voltage across his current sense resistor. Its power dissipation can thus be application optimized.Finally, the bulk input ripple ensures a natural frequency smearing which smooths the EMI signature.

特性 Features

• Quasi fixed TON, Variable TOFF Current Mode Control
• Natural frequency foldback
• Frequency foldback with Peak Current Compression
• Noise free & improved efficiency in light load
• Short circuit protection (latchedA version or auto restart B version)
• Independent of the auxiliary Winding
• Primary or secondary side regulation
• Dedicated Latch Input for OTP, OVP
• Low start-up current
• Natural frequency jittering
• Negative current sensing with programmable current sense resistor

应用 Application

• Auxiliary Power Supply
• Off-line battery chargers
• Printers
• Adapters

简介

NCP1351属于集成电路（IC）的ACDC转换器离线开关。由制造生产的NCP1351AC DC 转换器，离线开关该系列是元器件级控制产品，用于构建将交流市电转换为直流电（通常电压大幅降低）的设备。集成和未集成系统主要开关元件的器件均包括在内。由于高输入输出电压比，以及此类系统中通常需要隔离，这些器件通常与外部变压器配合使用。尽管通常使用定制变压器来实现此用途，但也有许多专门用于此用途的库存产品，请参见“开关转换器，SMPS 变压器”标题。