特点 单级、有源功率因数校正,高PF 值,低THD 高达90%的系统效率 ±5% LED 输出电流精度 优异的线电压调整率和负载调整率 电感电流临界连续模式 超低(10uA) 启动电流 LED 开路/短路保护 电流采样电阻开路保护 逐周期原边电流限流 芯片供电过压/欠压保护 自动重启功能 小体积的SOT23-6 封装 应用 GU10/E2 LED 球泡灯、射灯 LED PAR30、PAR38 灯 LED 日光灯 其它LED 照明 概述 MT6633 是一款带有源功率因数校正的高精度降 压型LED 恒流控制芯片,适用于85Vac-265Vac 全范 围输入电压的非隔离降压式LED 恒流电源。MT6633 集成有源功率因数校正电路,可以实现很高的功率因 数和很低的总谐波失真。由于工作在电感电流临界连 续模式,功率MOS 管处于零电流开通状态,开关损耗 得以减小,同时电感的利用率也较高。 MT6633 采用电流采样机制,可实现高精度输出 恒流控制。同时,芯片采用先进的线电压和负载电压 补偿技术,可以达到优异的线电压和负载调整率。线 电压补偿系数还可以通过外部元件灵活调整。 MT6633 具有多重保护功能以加强系统可靠性, 包括LED 开路保护、LED 短路保护、芯片供电过压保 护、欠压保护、电流采样电阻开路保护和逐周期限流 等。所有的保护状态都具有自动重启功能。 APPLICATIONS Offline AC/DC fly-back converter for Battery Charger Power Adapter Set-Top Box Power Supplies Open-frame SMPS GENERAL DEscriptION MT623 is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications. PWM switching frequency at normal operation is internally fixed and is trimmed to tight range. At no load or light load condition, the IC operates in extended ‘burst mode’ to minimize switching loss Lower standby power and higher conversion efficiency is thus achieved. VDD low start-up current and low operating current contribute to a reliable power on start-up and low standby design with MT623. MT623 offers complete protection coverage with auto-recovery including Cycle-by-Cycle current limiting (OCP), Over Load Protection (OLP), Over Temperature Protection (OTP), Over Voltage (fixed or adjustable) Protection (OVP) and VDD Under Voltage Lockout (UVLO). Excellent EMI performance is achieved. Frequency shuffling technique. The tone energy at below 20kHz is minimized in the design and audio noise is eliminated during operation. MT623 is offered in SOT23-6 package.