Switching regulator, control method thereof and power-supply device

1. A switching regulator configured to convert an input voltage input to an input terminal into a predetermined constant voltage by switching with at least two elements including a pair of switching elements or a switching element and a rectifying element, and output the converted voltage as an output voltage from an output terminal, comprising:

a comparison unit configured to compare a signal showing an oscillating frequency of the switching regulator with a signal showing a constant frequency; and

a driver configured to delay a pulse signal generated by feeding-back a control signal and an output signal of the switching regulator according to the comparison result by the comparison unit with a predetermined time, and switch the input voltage by using the at least two elements based on the pulse signal after the delay,

wherein the comparison unit includes an oscillation circuit configured to generate the signal showing a constant frequency, and output the signal, a frequency comparison circuit configured to compare the signal showing the oscillating frequency of the switching regulator with the signal showing a constant frequency, and output a signal corresponding to the comparison result, and a comparator configured to compare a proportional voltage proportional to the output voltage or a composite voltage of the proportional voltage and a ripple voltage generated by a ripple generation circuit with a predetermined reference voltage, and output a signal of the comparison result, and

the driver includes a delay circuit configured to delay the output signal of the comparator based on the signal corresponding to the comparison result with a delay time according to the comparison result, and output the output signal, and a driving circuit configured to generate a control signal to the at least two elements based on the output signal of the delay circuit, and output the control signal.

2. The switching regulator according to claim 1 further comprising a smoothing circuit including an inductor and a capacitor, configured to smooth the output voltage, wherein

the at least two elements are connected in series, and include a first switching element and a second switching element connected between the input voltage and a ground, and

the second switching element flows a current to the inductor when the first switching element is turned off.

3. The switching regulator according to claim 1 , wherein

the switching regulator is controlled such that the oscillating frequency of the switching regulator is set to be a frequency similar to a constant frequency generated inside or outside the switching regulator.

4. The switching regulator according to claim 1 , wherein

the frequency comparison circuit includes an EXOR circuit configured to output, with the signal showing the oscillating frequency of the switching regulator and the signal showing a constant frequency as inputs, a signal showing an EXOR calculation result of the signals, and an integration circuit configured to timely integrate the signal from the EXOR circuit, and output a signal corresponding to the comparison result.

5. The switching regulator according to claim 4 , wherein the frequency comparison circuit is configured to output the signal from the integration circuit as a voltage signal.

6. The switching regulator according to claim 5 , wherein the frequency comparison circuit includes a source follower circuit configured to convert the voltage signal from the integration circuit into a current signal.

7. The switching regulator according to claim 6 , wherein the delay circuit is configured to delay the output signal of the comparator based on the current signal with a delay time according to the current signal, and output the output signal.

8. The switching regulator according to claim 5 , wherein the delay circuit is configured to delay the output signal of the comparator based on the voltage signal with a delay time according to the voltage signal, and output the output signal.

9. A power-supply device comprising the switching regulator according to claim 1 .

10. A method of controlling a switching regulator, configured to convert an Input voltage input to an input terminal into a predetermined constant voltage by switching with at least two elements including a pair of switching elements or a switching element and a rectifying element, and output the converted voltage as an output voltage from an output terminal, comprising:

a step performed by a comparison unit of the switching regulator of comparing a signal showing an oscillating frequency of the switching regulator with a signal showing a constant frequency; and

a step performed by a driver of the switching regulator of delaying a pulse signal generated by feeding-back a control signal and an output signal of the switching regulator according to the comparison result by the comparison unit with a predetermined time, and switching the input voltage by using the at least two elements based on the pulse signal after the delay,

wherein the comparison unit includes an oscillation circuit configured to generate the signal showing a constant frequency, and output the signal, a frequency comparison circuit configured to compare the signal showing the oscillating frequency of the switching regulator with the signal showing a constant frequency, and output a signal corresponding to the comparison result, and a comparator configured to compare a proportional voltage proportional to the output voltage or a composite voltage of the proportional voltage and a ripple voltage generated by a ripple generation circuit with a predetermined reference voltage, and output a signal of the comparison result, and

the driver includes a delay circuit configured to delay the output signal of the comparator based on the signal corresponding to the comparison result with a delay time according to the comparison result, and output the output signal, and a driving circuit configured to generate a control signal to the at least two elements based on the output signal of the delay circuit, and output the signal.