Switching power supply and portable device

A switching power supply comprising

• a first switching power supply comprising:
• a first switching element connected to a power supply voltage and for performing ON and OFF operation;
• a first control circuit for performing ON and OFF control of the first switching element;
• a first coil by which an amount of current value which flows through the first switching element is controlled;
• a first capacitor connected to the first coil and for performing a rectifying operation with the first coil;
• an oscillator for outputting a first oscillator signal for controlling the first switching element into ON for every constant period to the first control circuit;
• a first of first comparator for comparing a first current detection voltage which transforms a detection current which flows through the first coil into a voltage and a first feedback voltage according to the difference of a voltage according to a first output voltage outputted from a connection node of the first capacitor and the first coil, with a reference voltage;
• and a second of first comparator for comparing a first threshold voltage set as a voltage value which is lower than the power supply voltage and is higher than the first current detection voltage, with the first feedback voltage;
• and
• a second switching power supply comprising:
• a second switching element connected to the power supply voltage and for performing ON and OFF operation;
• a second control circuit for performing ON and OFF control of the second switching element;
• a second coil by which an amount of current value which flows through the second switching element is controlled;
• a second capacitor connected to the second coil and for performing a rectifying operation with the second coil;
• an oscillator for outputting a second oscillator signal for controlling the second switching element into ON for every constant period to the second control circuit;
• a first of second comparator for comparing a second current detection voltage which transforms a detection current which flows through the second coil into a voltage and a second feedback voltage according to the difference of a voltage according to a second output voltage outputted from a connection node of the second capacitor and the second coil, with the reference voltage;
• and a second of second comparator for comparing a second threshold voltage set as a voltage value which is lower than the power supply voltage and is higher than the second current detection voltage, with the second feedback voltage, wherein
• the first switching power supply and the second switching power supply are provided with a two-channel configuration in parallel, and operate on a frequency in synchronization with the first oscillator signal and the second oscillator signal from the oscillator with which the 180 degrees phase shifts, respectively at the time of PWM operation.

A portable device comprising a switching power supply, the switching power supply comprising:

• a switching element which is connected to a power supply voltage and performs ON and OFF operation;
• a control circuit for performing ON and OFF control of the switching element;
• a coil by which the amount of current value which flows through the switching element is controlled;
• a capacitor which is connected to the coil and performs a rectifying operation with the coil;
• an oscillator for outputting an oscillator signal for controlling the switching element into ON for every constant period to the control circuit;
• a first comparator for comparing a current detection voltage which transforms a detection current which flows through the coil into a voltage, and the feedback voltage according to a difference of a voltage according to an output voltage outputted from a connection node between the capacitor and the coil with a reference voltage;
• and
• a second comparator for comparing a threshold voltage set as a voltage value which is higher than the current detection voltage and is lower than the power supply voltage, with the feedback voltage.

A portable device comprising a switching power supply, the switching power supply comprising

• a first switching power supply comprising:
• a first switching element connected to a power supply voltage and for performing ON and OFF operation;
• a first control circuit for performing ON and OFF control of the first switching element;
• a first coil by which an amount of current value which flows through the first switching element is controlled;
• a first capacitor connected to the first coil and for performing a rectifying operation with the first coil;
• an oscillator for outputting a first oscillator signal for controlling the first switching element into ON for every constant period to the first control circuit;
• a first of first comparator for comparing a first current detection voltage which transforms a detection current which flows through the first coil into a voltage and a first feedback voltage according to the difference of a voltage according to a first output voltage outputted from a connection node of the first capacitor and the first coil, with a reference voltage;
• and a second of first comparator for comparing a first threshold voltage set as a voltage value which is lower than the power supply voltage and is higher than the first current detection voltage, with the first feedback voltage;
• and
• a second switching power supply comprising:
• a second switching element connected to the power supply voltage and for performing ON and OFF operation;
• a second control circuit for performing ON and OFF control of the second switching element;
• a second coil by which an amount of current value which flows through the second switching element is controlled;
• a second capacitor connected to the second coil and for performing a rectifying operation with the second coil;
• an oscillator for outputting a second oscillator signal for controlling the second switching element into ON for every constant period to the second control circuit;
• a first of second comparator for comparing a second current detection voltage which transforms a detection current which flows through the second coil into a voltage and a second feedback voltage according to the difference of a voltage according to a second output voltage outputted from a connection node of the second capacitor and the second coil, with the reference voltage;
• and a second of second comparator for comparing a second threshold voltage set as a voltage value which is lower than the power supply voltage and is higher than the second current detection voltage, with the second feedback voltage, wherein
• the first switching power supply and the second switching power supply are provided with a two-channel configuration in parallel, and operate on a frequency in synchronization with the first oscillator signal and the second oscillator signal from the oscillator with which the 180 degrees phase shifts, respectively at the time of PWM operation.