一种具有过流保护功能的振荡器设计  

Design a Oscillator with current limit protection

作　　者：王慧芳[1] 陈程[1] 徐祥柱[1] 周泽坤[1] 张波[1] 

机构地区：[1]电子科技大学电子薄膜与集成器件国家重点实验室,四川成都610054

出　　处：《中国集成电路》2011年第10期39-44,共6页China lntegrated Circuit

摘　　要：提出了一种用于峰值电流模式控制的高压BUCK变换器的振荡器,并具有特殊电流限保护功能。在BUCK变换器正常工作时,该振荡器提供频率为340KHz的时钟信号;当振荡器处于异常状态,如负载过重或输出电压较低时,振荡器频率会随着输出电压的降低逐渐减小,该振荡器可以有效地防止电流失控现象的发生,并且减小了在异常情况时系统的功耗,同时也克服了功率管在电流过大时烧毁的危险;另外该振荡器还提供具有前沿消隐功能的斜坡补偿信号。该电路是基于CSMC的0.6μm 25V BCD工艺实现的,并通过电路模拟软件Hspice对振荡器电路完成了仿真验证。A novel oscillator was presented based on the high power buck converters and it has a function of currentlimit protection. When converter work normally, the oscillator provides a 340KHz clock signal. However in the abnormal state, such as overload or output shorted, the frequency of the oscillator reduced as the output voltage droped. The oscillator may be effectively prevent the phenomenon of current uncontrolled, save up the compensation of system at the abnormal situation, and decrease the risk of damaging the power transistor. At the same time, the oscillator provides a sawtooth signal for slope compensation with LEB function. This circuit has been designed in CSMC 0.6- μm 25V BCD process and verified by Hspice simulation.

关 键 词：振荡器 BUCK变换器 负载过重 前沿消隐 

分 类 号：TN752[电子电信—电路与系统]