| 摘要 |
PURPOSE:To prevent the performance of a stabilized power source from deteriorating by estimating and detecting a load current on the basis of the heating value and voltage drop of the control element of the stabilized power source. CONSTITUTION:Detected voltages of temperature sensors 44 and 46 and voltage sensors 48 and 50 are supplied to amplifiers 52 and 54, and 56 and 58, a differential amplifier 60 calculates the difference between sensor output voltages TS and TH, and a differen tial amplifier 62 calculates the diffference between sensor output voltages Vin and Vout. Then, a divider 64 divides the output voltage DELTAT5H of the amplifier 60 by the output voltage DELTAV of the amplifier 62 to generate an output voltage corresonding to the load current. The output voltage of the divider is supplied to one-input sides of comparators 66 and 68 and reference voltages VMAX and VMIN correspoinding to the maximum permissible value and minimum permissible value of the load current are supplied to the other-input sides. The comparators 66 and 68 outputs a comparison output when the output voltage of the divider 64 rises below the voltage VMAX and drops above the voltage VMIN respectively. When at least either comparator outputs a comparison signal, an OR circuit 70 supplies an alarm control signal to an alarm 72 to take a countermessure to protect a load immediately, thereby preventing the performance of the stabilized power source from deteriorating.
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