Boost-type switching power device

A boost-type switching power device which obtains a dc output by connecting a rectifying diode to the output side of an inductance element, connected in series to a main switching element, the device comprising:

• an auxiliary switching element which controls the operation of said main switching element by using a feedback signal in accordance with the dc output;
• and a constant-current circuit comprising a plurality of active elements, which are provided between the said rectifying diode and the output terminal;
• and wherein,
• when there is an overload on the output side, the operation of the active elements comprising said constant-current circuit controls said auxiliary switching element, switching said main switching element off and thereby stopping the boost function, and, in addition, the output is controlled by the constant-current circuit.

A boost-type switching power device which obtains a dc output by connecting a rectifying diode to the output side of an inductance element, connected in series to a main switching element, the device comprising:

• a control circuit which controls the operation of said main switching element by using a feedback signal from the output;
• and a constant-current circuit comprising a plurality of active elements, which are provided between the said rectifying diode and the output terminal;
• and wherein,
• when the current supplied to the output side has become overloaded, the operation of the active elements comprising said constant-current circuit controls the operation of said control circuit so as to switch off said main switching element and thereby stop the boost function, and, in addition, a current restricted to a predetermined size is supplied to the output side.