CONTROL METHOD FOR OVERCURRENT PROTECTING OPERATION OF STEP-DOWN DC-DC CONVERTER, JUDGING INTEGRATED CIRCUIT FOR OVERCURRENT PROTECTING OPERATION OF STEP-DOWN DC-DC CONVERTER, JUDGING CIRCUIT MODULE FOR OVERCURRENT PROTECTING OPERATION OF STEP-DOWN DC-DC CONVERTER, CONTROL INTEGRATED CIRCUIT OF STEP-DOWN DC-DC CONVERTER, AND BOARD FOR COMPUTER

摘要

PROBLEM TO BE SOLVED: To prevent conversion efficiency drop of a step-down DC-DC converter that outputs large low-voltage current and enhance the accuracy of the threshold at which the overcurrent protecting function is actuated.;SOLUTION: A sensor resistor Rs is inserted on the side of an input portion Vin and using current and voltage detected at an input current detecting portion 1 and an input voltage detecting portion 2, it is judged whether operation is in a normal operation range. If it is judged that operation is out of the normal operation range, a stop signal is outputted from an overcurrent protecting operation judging portion 3 to a switch control portion 4. Since the sensor resistor is inserted in the input portion side, loss due to the resistor is reduced. Since the accurate sensor resistor is used to detect currents and voltages, detecting accuracy is ensured. Since it is judged in terms both of current and of voltage whether operation is in the normal operation range, fluctuation in the input voltage can be coped with. Since the sensor resistor is placed on the input side, the number of parts can be reduced by one on the output side where large currents are passed, and thus the degree of freedom in designing and the heat radiating capability can be enhanced.;COPYRIGHT: (C)2002,JPO