Switching control circuit and switching power supply apparatus including standby mode setting mechanism

A switching control circuit comprising:

• a semiconductor integrated circuit configured to include a plurality of external terminals and be provided in a power converter circuit of a switching power supply apparatus to control a switching element;
• wherein
• the plurality of external terminals include a polarity detection terminal, into which a polarity inversion timing signal indicating a change in a polarity of a current flowing through or a voltage generated in an inductor or a transformer of the power converter circuit due to an operation of the switching control circuit is input, and a feedback terminal into which a feedback signal used to detect and control an output voltage obtained due to an operation of the switching control circuit is input;
• the switching control circuit includes:
• a switching element control mechanism configured to perform switching control of the switching element on the basis of a signal of the polarity detection terminal and a voltage of the feedback terminal;
• a control mode switching mechanism configured to switch between a control mode of the switching element when a load of the power converter circuit is in a standby state and a control mode of the switching element when the load is in a normal load state;
• and
• a standby mode setting mechanism configured to, when a power supply voltage input to the switching control circuit has exceeded a predetermined value, start to detect, as a determination target signal, a voltage induced in an external circuit that is connected to the polarity detection terminal or the feedback terminal and includes at least a resistance element or a semiconductor element, and set a validity/invalidity of a control mode that is switched when the control mode switching mechanism is in the standby state or set a type of a control mode in a standby state, in response to the determination target signal in a predetermined detection time period in which the determination target signal is detected.