SWITCHING REGULATOR AND METHOD FOR CONTROLLING THE SWITCHING REGULATOR
By controlling the duty of a switching pulse signal and a switching frequency of the signal in response to changes in load current, the ripple of the output voltage can be reduced and switching losses can be reduced and thus a switching regulator that is efficient can be provided.
1 . A switching regulator comprising:
a control circuit including a switching drive voltage generating circuit to generate a switching signal to control a switching element to be a connected a load, wherein the control circuit is further configured to control both a duty ratio of the switching signal and a frequency of the switching signal in accordance with an amount of a load current.
2 . The switching regulator as claimed in claim 1 , wherein the control circuit controls a pulse width of the switching signal to be relatively narrower as the load current becomes larger, and controls the pulse width of the switching signal to be relatively wider when the load current becomes smaller.
3 . A switching regulator comprising:
a switching element to be connected to a load, to generate an output voltage of the switching regulator;
an error amplifier to output an error voltage signal obtained by amplifying a voltage difference between a reference voltage and a feedback voltage which is proportional to the output voltage output to the load;
a slope voltage generation circuit to generate a square wave signal and a slope voltage that is varied in accordance with an amount of the output current;
a PWM comparator to compare the error voltage signal with the slope voltage and output a PWM signal; and
a switching driving voltage generation circuit to generate a switching driving voltage that controls the switching element in accordance with the square wave and the PWM signal.
4 . The switching regulator as claimed in claim 3 , further comprising:
a current control circuit to control the amount of the output current, the current control circuit including:
a reference current circuit to output a reference current value, for determining a lowest frequency of the slope voltage, to the slope voltage generating circuit;
a current setting circuit to set a load current value of the load and a variable current value to vary inclination of the slope voltage based on an external signal; and
a load current control circuit to control an amount of the load current flowing through the load to the current value set by the current setting circuit.
5 . The switching regulator as claimed in claim 4 , wherein the slope voltage generation circuit comprises:
a current source to flow a current corresponding to the variable current value set by the current setting circuit;
a capacitor and a discharge switch connected in parallel to each other, the combination of the capacitor and discharge switch connected in parallel being connected in series with the current source;
a pulse generating circuit to generate the square wave signal based on the slope waveform signal slope voltage having an inclination which is variable depending on an amount of the current that flows from the current source; and
a slope gradient control circuit to control the inclination of the slope voltage via the pulse generating circuit.
6 . A method performed by a switching regulator for controlling a switching element connecting a load, to generate an output voltage to the load, the method comprising:
generating a driving voltage to control both a duty ratio of the switching signal and a frequency of the switching signal in accordance with an amount of a load current flowing through the load; and
applying the driving voltage to the switching element.