OnSemi NCP1271 19V，3.0A通用AC－DC适配器设计方案

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。

The NCP1271 represents a new, pin to pin compatible, generation of the successful 7−pin current mode NCP12XX product series. The controller allows for excellent stand by power consumption by use of its adjustable Soft−Skip mode and integrated high voltage startup

FET. This proprietary Soft−Skip also dramatically reduces the risk of acoustic noise. This allows the use of inexpensive transformers and capacitors in the clamping network. Internal frequency jittering,ramp compensation, timer−based fault detection and a latch input make this controller an excellent candidate for converters where ruggedness and component cost are the key constraints.

NCP1271主要特性：

• Fixed−Frequency Current−Mode Operation with Ramp Compensation and Skip Cycle in Standby Condition

• Timer−Based Fault Protection for Improved Overload Detection

• “Soft−Skip Mode” Technique for Optimal Noise Control in Standby
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