UC2845B中文资料高性能电流模式 PWM 控制器数据手册ONSEMI规格书

描述 Description

The UC3844B, UC3845B series are high performance fixed frequency current mode controllers. They are specifically designed for Off-Line and dc-to-dc converter applications offering the designer a cost-effective solution with minimal external components. These integrated circuits feature an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle-by-cycle current limiting, a latch for single pulse metering, and a flip-flop which blanks the output off every other oscillator cycle, allowing output deadtimes to be programmed from 50% to 70%. These devices are available in an 8-pin dual-in-line and surface mount (SO-8) plastic package as well as the 14-pin plastic surface mount (SO-14). The SO-14 package has separate power and ground pins for the totem pole output stage. The UCX844B has UVLO thresholds of 16 V (on) and 10 V (off), ideally suited for off-line converters. The UCX845B is tailored for lower voltage applications having UVLO thresholds of 8.5 V (on) and 7.6 V (off).

特性 Features

• Trimmed Oscillator for Precise Frequency Control
• Oscillator Frequency Guaranteed at 250 kHz
• Current Mode Operation to 500 kHz Output Switching Frequency
• Output Deadtime Adjustable from 50% to 70%
• Automatic Feed Forward Compensation
• Latching PWM for Cycle-By-Cycle Current Limiting
• Internally Trimmed Reference with Undervoltage Lockout
• High Current Totem Pole Output
• Undervoltage Lockout with Hysteresis
• Low Startup and Operating Current
• Pb-Free Packages are Available

简介

UC2845B属于集成电路（IC）的PMIC-稳压器-DCDC开关式控制器。由制造生产的UC2845BDC-DC 开关控制器PMIC（电源管理集成电路）DC 到 DC 开关式控制器是用于高效率电路的稳压 IC，其配置为生成高于（突升或步升）或低于（突降或步降）输入电源的输出电源电压。其他拓扑结构可能包括：降压-升压、反激、正激、Cuk、SEPIC、全桥、半桥和推挽式。这些器件不同于需要最小电压并“烧尽”多余电压的线性稳压器。