Patent ID: 7974060

Claim:
An overcurrent limitation and output short-circuit protection circuit of a DC stabilized power supply circuit that drives an output transistor so as to make an output voltage constant based on an output of a differential amplifier that amplifies a difference between a reference voltage and a voltage proportional to the output voltage, the overcurrent limitation and output short-circuit protection circuit comprising: a proportional output current generation unit that generates a current proportional to a current flowing to the output transistor; a first current voltage conversion unit that converts the output current of the proportional output current generation unit into a voltage; a first power supply terminal; an output terminal; a second power supply terminal; a second current voltage conversion unit provided between the first power supply terminal and the second power supply terminal; a control unit that operates based on a difference between the voltage generated at the first current voltage conversion unit and a voltage generated at the second current voltage conversion unit; and one or more switching elements; wherein the proportional output current generation unit and the first current voltage conversion unit are connected in series between the first power supply terminal and the output terminal, and a current flowing to the second current voltage conversion unit is changed by the one or more switching elements in a stepwise manner based on the output voltage of the output transistor when supplying a current, thereby changing the voltages generated at both ends of the second current voltage conversion unit.