原标题：基于ON NCP4371的18W QC3.0 充电器方案

　　该设计采用了NCP1361 PWM IC、NCP4305同步整流和具有CC/CV控制的NCP437 1 QC3.0识别芯片，该设计支持高通QC2.0和QC3.0快速充电器。NCP4371是一个USB二次侧快速充电控制器，支持高通快速充电QC3.0高电压，专用充电端口(HVDCP)A类和B类规范。NCP4371允许选择AC-DC USB的输出电压。

　　基于来自便携式设备(PD)的命令的适配器动力的选择更高的充电电压将降低充电，给定功率电平的电流导致IR降低提高了系统效率。QC3.0的另一个优点是减少了由于电池充电时间和PD系统成本降低选择最佳充电电压的能力。USB总线电压可以从3.6 V到20 V的分级阶梯根据负载需求控制输出。输出电流限制不超过最大允许功率水平。

　　场景应用图

　　展示板照片

　　方案方块图

　　核心技术优势

　　1、 支持高通QC3.0 HVDCP A/B类

　　2、 输出5V/2.5A, 9V/2A and 12V/1.5A

　　3、 高效率二次同步整流控制

　　4、 具有谷值切换的准谐振电流模式控制

　　方案规格

　　1、5V输出时候空载功耗<75mW

　　2、在90Vac输入的时候启动10M启动电阻，启动时间<1.5S

　　3、支持USB输出电容器放电功能

　　4、平滑输出电压转换

　　5、支持外部2200μF容性负载启动

　　6、宽工作电压输入范围：2.2V至28V

　　技术文档

　　NCP1361: Low Power Offline Constant Current PWM Current-Mode Controller

　　The NCP1361 offers a new solution targeting output power levels from a few watts up to 20 W in a universal-mains flyback application. Thanks to a novel method this new controller saves the secondary feedback circuitry for constant current regulation while achieving excellent line and load regulation with traditional opto coupler and TL431 voltage reference. The NCP1361 operates in valley lockout quasi-resonant peak current mode control mode at high load to provide high efficiency. When the power on the secondary side starts to diminish, the controller automatically adjusts the duty-cycle then at lower load the controller enters in pulse frequency modulation at fixed peak current with a valley switching detection. This technique allows keeping the output regulation with tiny dummy load. Valley lockout at the first 4 valleys prevent valley jumping operation and then a valley switching at lower load provides high efficiency.

　　特性

　　No frequency clamp, 80 or 110 kHz Maximum Switching Frequency

　　Quasi-Resonant with Valley Switching Operation

　　Fixed Peak Current & Deep frequency foldback @ light load operation

　　Wide Operation VCC range (up to 28 V)

　　Cycle by Cycle peak current limit

　　CS & Vs/ZCD pin Short and Open Protection

　　Internal Temperature Shutdown

　　Constant Current Primary-side feedback eliminates secondary controller

　　±10% Current Regulation

　　Clamped Gate-drive Output for Mosfet

　　Built-in soft-start

　　Low Start-up current ( 2 μA typ.)

　　Less than 30 mW No-Load Performance at High Line

　　These are Pb-Free Devices

　　优势

　　Prevent high frequency interference with a touchscreen

　　QR architecture offers high efficiency operation

　　Low light load consumption

　　Design flexibility

　　Safe operation

　　应用

　　AC-DC USB Charging

　　终端产品

　　Cell Phones

　　Tablets

　　Portable Devices