Direct-current power-supply apparatus, control circuit thereof and semiconductor integrated circuit device for power supply

A direct-current power-supply apparatus comprising a switching converter and a control circuit wherein:

• said switching converter comprises:
• a main switch device for generating a pulse voltage from a direct-current input;
• a synchronous-rectification circuit for converting said pulse voltage into a direct-current voltage;
• a reverse-current-blocking device for blocking a reverse current from a load;
• and
• an output terminal connected to the load through said reverse-current-blocking device;
• said control circuit is used for controlling said switching converter by detection of a voltage and a current, which are output by said switching converter, so as to set said output voltage at a predetermined level;
• said control circuit comprises:
• a maximum-current follow-up control unit for controlling a current to be borne by said switching converter in a parallel operation;
• a PWM formation unit for driving said main switch device employed in said switching converter;
• a synchronous-rectification control unit for generating a signal for driving said synchronous-rectification circuit;
• and
• a driving control unit for controlling an operation to drive said reverse-current-blocking switch device;
• and
• said maximum-current follow-up control unit, said PWM formation unit, said synchronous-rectification control unit and said driving control unit operate with an electric potential at said output terminal of the switching converter used as a reference electric potential.

A control circuit for controlling a switching converter by detection of a voltage and a current, which are output by said switching converter, so as to set said output voltage at a predetermined level wherein:

• said switching converter comprises:
• a main switch device for generating a pulse voltage from a direct-current input;
• a synchronous-rectification circuit for converting said pulse voltage into a direct-current voltage;
• a reverse-current-blocking device for blocking a reverse current from a load;
• and
• an output terminal connected to the load through said reverse-current-blocking device;
• said control circuit comprises:
• a maximum-current follow-up control unit for controlling a current to be borne by said switching converter in a parallel operation;
• a PWM formation unit for driving said main switch device employed in said switching converter;
• a synchronous-rectification control unit for generating a signal for driving said synchronous-rectification circuit;
• and
• a driving control unit for controlling an operation to drive said reverse-current-blocking switch device;
• and
• said maximum-current follow-up control unit, said PWM formation unit, said synchronous-rectification control unit and said driving control unit operate with a common electric potential used as a reference electric potential.