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OnSemi公司的NCP1271是一款最新的固定頻率電流模式PWM開關(guān)控制器，具有為低級聲頻噪聲提供可調(diào)節(jié)的Soft-Skip待機操作模式，為節(jié)省待機功耗內(nèi)部集成高壓啟動，過載故障檢測定時器，內(nèi)部鎖保護功能特性。本文首先介紹NCP1271、基本特性、內(nèi)部框圖及應(yīng)用領(lǐng)域，并給出相應(yīng)設(shè)計方案的設(shè)計原理圖、元器件列表及PCB元件布局圖。 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 • Internal High−Voltage Startup Current Source for Lossless Startup • _5% Current Limit Accuracy over the Full Temperature Range • Adjustable Skip Level • Internal Latch for Easy Implementation of Overvoltage and Overtemperature Protection • Frequency Jittering for Softened EMI Signature • +500 mA/−800 mA Peak Current Drive Capability • Sub−100 mW Standby Power can be Achieved • Pin−to−  in Compatible with the Existing NCP120X Series• This is a Pb−Free Device NCP1271應(yīng)用領(lǐng)域： • AC−DC Adapters for Notebooks, LCD Monitors • Offline Battery Chargers • Consumer Electronic Appliances STB, DVD, DVDR 
圖1. NCP1271內(nèi)部方框圖 NCP1271ADAPGEVB方案介紹： This evaluation board user’s manual presents an example circuit using the NCP1271 (65 kHz version) in a flyback topology. The design steps and subsequent measurements are also included. An Excel based design worksheet is available at www.onsemi.com. The measurements show that the 19 V, 3.0 A circuit delivers above 85% across a universal input (85 to 265 Vac).The no load standby consumption is 83 mW at 230 Vac and the light load operation is greater than 75% efficient. NCP1271ADAPGEVB方案原理圖：
圖2. NCP1271ADAPGEVB方案原理圖 NCP1271ADAPGEVB方案材料清單：
PCB元件布局圖：
Top View
Bottom View 詳細資料如下 
EVBUM2145-D.PDF
(808.74 KB)
NCP1271-D.pdf
(233.83 KB)
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