An overcurrent protection circuit for the DC power supply circuit, over-current protection circuit, according to the differential amplifier (M12) output driver output transistor (M16), the output voltage is fixed, the differential amplifier and the output voltage is proportional to the voltage and the reference voltage of the difference; characterized in that the overcurrent protection circuit includes: the proportion of the output current generating device (M11), and through the output transistor (M16) current proportional to the current; current / voltage converter (R11), the ratio of the output current generating device (M11) of the output current is converted to voltage; switch device (M12), when the output voltage regulation voltage increases, the proportion of output current generation device (M11) output A current supplied to the current / voltage converter (R11), and when the output voltage is specified when the voltage is low, cut off the supply; and a control device (M13), according to the proportion of the output current generating device (M11) of the output voltage on the drain electrode, control the output transistor (M16) the output current.
【技术实现步骤摘要】
本专利技术涉及直流稳压电源电路中的过流保护电路。
技术介绍
图1表示以往的过流保护电路的电路例1，如图所示，该电路由以下各部分构成稳压电源，用电阻R1，R2及R3对输出电压Vout进行分压，用差分放大器AMP放大上述所得分压电压与基准电压Vref的差分，根据上述放大信号来控制输出晶体管M1，使得Vout固定；差动放大块，对晶体管M6的输入是由输出电压的分压所得的电压，对晶体管M5的输入为电压变换后的电压，晶体管M7将偏置电压施加于上述电压变换过的电压上，成为源极跟随器，其中，用电阻R4对流过输出晶体管M1的电流按规定比率得到流过监测晶体管M2的电流进行电压变换；以及控制晶体管M8，通过其输出来控制动作，在运算放大器输出与电源电压VDD间控制输出晶体管M1的控制线。下面参照图2的输出特性说明图1电路例的工作。通常工作时，输出从无负荷到某规定负荷，流过晶体管M2的电流小，晶体管M5的输入电压比晶体管M6的输入电压低很多，控制晶体管M8的输入为高电位，由于控制晶体管M8截止，所以输出电压Vout固定。接着，随着输出电流Iout增大，晶体管M5的输入电压上升，控制晶体...
【技术保护点】
【技术特征摘要】
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