UC3844芯片的介绍
UC3844是美国Unitrode公司生产的一种高性能单端输出式电流控制型脉宽调制器芯片,由该集成电路构成的开关稳压电源与一般的电压控制型脉宽调制开关稳压电源相比具有外围电路简单、电压调整率好、频响特性好、稳定幅度大、具有过流限制、过压保护和欠压锁定等优点。其内部电路结构如图1所示。
该芯片的主要功能有:内部采用精度为±2.0%的基准电压为5.00V,具有很高的温度稳定性和较低的噪声等级;振荡器的振荡频率可达500kHz。内部振荡器的频率同脚8与脚4间电阻Rt、脚4的接地电容Ct的关系如式(1)所列,即
其内部带锁定的PWM(Pulse Width Modulation),可以实现逐个脉冲的电流限制;具有图腾柱输出,能提供达1A的电流直接驱动MOSFET功率管。
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