Switching power supply control circuit

A switching power supply control circuit configured to operate a switching power supply circuit so as to be switched into a normal state or a stand-by state, comprising:

• a first comparator which has a feedback signal of an output voltage detecting circuit inputted to compare the inputted feedback signal with a feedback reference voltage corresponding to a specified control voltage, the detecting circuit detecting an output voltage of the switching power supply circuit, and outputs a voltage decision signal indicating whether the output voltage of the switching power supply circuit reaches the specified control voltage or not;
• a second comparator which has a switching instruction signal inputted to compare the inputted switching instruction signal with an operating state decision reference voltage signal, the switching instruction signal being produced by a signal generating unit operated by an output voltage of the switching power supply circuit, and outputs a switching decision signal indicating whether the switching instruction signal is a signal instructing a stand-by operation or not;
• a decision circuit which is connected to the first comparator and the second comparator and, after the voltage decision signal outputted from the first comparator indicates that the output voltage of the switching power supply circuit reaches the specified control voltage, makes the switching decision signal outputted from the second comparator effective;
• and
• a control circuit which is connected to the decision circuit to operate the switching power supply circuit in a normal state until the output voltage reaches the specified control voltage and, after the output voltage reaches the specified control voltage, operate the switching power supply circuit in an operation state based on the instruction of the switching instruction signal.