中文摘要：

基于UMC 0.25 μm BiCMOS工艺,设计了一款投影机过温保护电路.利用三极管BE结电压的负温度特性实现温度的检测,与传统的过温保护电路不同,该保护电路巧妙地利用比较器的内部正反馈实现热滞回,提高了迟滞的精确度.HSPICE仿真结果表明,该电路能很好地抑制电源电压变化造成的热关断和迟滞阈值点的漂移,性能稳定、可靠.电路能在温度过高时准确地将系统关断,达到保护光源和液晶板的目的,最大限度地保证了投影机的使用寿命.

英文摘要：

An over-temperature protection （OTP） circuit for projectors is proposed based on UMC 0.25 μm BiCMOS proeess. The temperatun, detec- tion is achieved using the negative temperature-coefficient characteristic of base-emitter （BE） junction voltage. Different from the traditi,mal OTP cir- cuit, the thermal hysteresis of the proposed circuit is realized through the internal positive feedback of a comparator. Thus the precision of the hysferesis is improved. Simulation using HSP1CE software shows that, the drifts of thermal shutdown and hysteresis thresholds are well rejected. The proposed cir- cuit has steady and reliable performances. It can shut down the system accurately when the device is over-temperature. The protection of lamp house and liquid crystal board is achieved and the useful life of the projector is guaranteed.