Switching power supply apparatus and semiconductor device
View Patent ↗Provided is a switching power supply apparatus that shifts to an OFF mode when electronic equipment is on standby, and includes: an OFF mode delay circuit that delays shifting to the OFF mode; and an electric storage unit and a power supply circuit that function as a power supply source of an OFF mode control circuit. With the configuration, the power consumption can almost be eliminated, and the switching power supply apparatus can start without any charge in an electricity storage component such as a primary battery or a secondary battery.
1. A switching power supply apparatus comprising:
a switching element to which an input voltage is applied;
an input/output converting circuit that converts the input voltage switched by the switching element into an output voltage, and supply power corresponding to the output voltage to a loading apparatus;
a switching control circuit that controls a switching operation of the switching element, and has an OFF mode for stopping the switching operation, the switching control circuit being placed in the OFF mode when an OFF mode cancellation signal for cancelling the OFF mode is not input to an OFF terminal of the switching control circuit;
an OFF mode control circuit that outputs the OFF mode cancellation signal according to a signal from the loading apparatus;
an electric storage unit that supplies power to the OFF mode control circuit in the OFF mode;
a power supply circuit that supplies the OFF mode control circuit with power corresponding to the output voltage; and
an OFF mode delay circuit that delays the placing of the switching control circuit in the OFF mode for a first length of time when the input voltage is supplied for startup in the case where the OFF mode cancellation signal is not input to the OFF terminal,
wherein the first length of time is greater than or equal to a length of time required for the OFF mode cancellation signal that is output from the OFF mode control circuit according to the startup with the input voltage to be input to the OFF terminal since timing of the startup with the input voltage.
2. The switching power supply apparatus according to claim 1 , further comprising:
a DC connector for connecting or disconnecting the loading apparatus,
wherein the OFF mode control circuit, the electric storage unit, and the power supply circuit are disposed closer to the loading apparatus than to the DC connector, and
in the case where the DC connector is disconnected, when the OFF mode cancellation signal is not input to the OFF terminal, and the input voltage is supplied for the startup, the switching control circuit is placed in the OFF mode after the first length of time has elapsed since the timing of the startup with the input voltage.
3. The switching power supply apparatus according to claim 1 , further comprising an OFF mode forced cancellation circuit that cancels the OFF mode independently of whether the OFF mode cancellation signal is input to the OFF terminal.
4. The switching power supply apparatus according to claim 3 , further comprising:
an input interruption detection circuit that outputs an input interruption detection signal to the OFF mode delay circuit when application of the input voltage is interrupted,
wherein the OFF mode forced cancellation circuit cancels the OFF mode according to output of the input interruption detection signal.
5. The switching power supply apparatus according to claim 1 , wherein the electric storage unit is configured to supply power to the loading apparatus.
6. A semiconductor device for controlling a switching power supply apparatus, the semiconductor device being included in the switching power supply apparatus, the semiconductor device comprising the switching control circuit according to claim 1 .