Output voltage-drop detecting apparatus technical field

An output voltage-drop detecting apparatus connected to a stabilized DC power source in order to monitor the output voltage of the power source and detect a drop in the output voltage, comprising:

• stabilized DC power source means for receiving AC power and producing a stabilized DC output across two output ports, said stabilized DC power source means including a rectifying and smoothing circuit, power control circuit means connected between the rectifying and smoothing circuit and the output ports for regulating the output voltage in response to a control signal, reference voltage generating circuit means for generating a reference voltage by resistance-dividing a reference voltage source, and error amplifier means for generating the control signal in accordance with the difference between the reference voltage and the voltage at one of the output ports;
• and
• output voltage drop detecting means for emitting a detection output signal should the voltage across the output ports of the stabilized DC power source means drop past a predetermined level, said output voltage drop detecting means including first and second resistors series-connected between the output of the reference voltage generating means and one of the output ports, said first and second resistors being connected at an intermediate connection point, and a comparator having a first input connected to the intermediate connection point and a second input connected to one of the output ports, the output of the comparator serving as the detection output signal.