多种保护电路的低压差线性稳压器设计及仿真

Design and Simulation of LDO Regulator Based on Multiple Protection Circuits

针对电路系统中对低压差线性稳压器高稳定性要求,以及在使用过程中过热及输出电流过大而使电路遭到破坏.提出了一款具有过温保护、短路及限流保护功能的LDO,采用电压与温度成正比的器件感知电路中的温度,将正温度系数电压与恒定电压相比较作为控制信号,利用将输出电流镜像到某个电阻上,其电压与一个恒定电压相比较,调节流过功率管的电流,以达到限流保护.结果表明:过温保护电路的迟滞温度为30℃;过流保护电路在负载电流达到812mA时开启保护;短路保护电路当输出电压小于0.7V时开启保护.在0.1μF电容负载上进行了仿真验证.

Aiming at the special request for high stability of low-dropout voltage and linear regulators （LDO） ,and the destroyed because of thermal and over load current ,the LDO with function of protection of over temperature ,short-circuit and current limiting is proposed .In the over temperature protection module , the temperature of the circuit is perceived throuth the voltage of the device w hich is proportional with temperature ,the proportional voltage is compared with the constant voltage ,the result is as the adjust signal to realize over temperature protection .In short-circuit and current limiting protection module ,by comparing constant voltage with the voltage whose current produced through mirroring to the current of PMOS ,the result is to be the adjust signal to protect circuit .The Hysteresis temperature of over-temperature protection circuit is 30 ℃ .T he curruent limiting protection circuit starts working when load current is 816 mA .Short circuit protection circuit starts working when output voltage is smaller than 0 .7 V .The designed LDO system is simulated under the load capacitance of 0 .1 μF .