Patent ID: 8760137
Filing Date: 2014-06-24
Classification: H02M

Abstract:
1. A DC-DC converter control circuit to control a DC-DC converter including a power supply terminal to which an input voltage is input, a ground terminal, an output terminal to output an output voltage, a first switching element and a second switching element connected in series between the power supply terminal and the ground terminal, an inductor connected between the output terminal and a junction node between the first switching element and the second switching element, and a first capacitor connected between the output terminal and the ground terminal, the DC-DC converter control circuit comprising: a first feedback circuit to detect an output voltage of the DC-DC converter; and generate a first feedback voltage indicating a direct-current component of an inductor current flowing through the inductor of the DC-DC converter based on the output voltage; a second feedback circuit to generate a second feedback voltage indicating an alternating-current component of the inductor current flowing through the inductor of the DC-DC converter based on the input voltage and the output voltage of the DC-DC converter; a synthesis circuit to add the first feedback voltage to the second feedback voltage to generate a third feedback voltage; a reference voltage generator circuit to generate a predetermined first reference voltage corresponding to a desired output voltage of the DC-DC converter; a first comparator to compare the third feedback voltage with the first reference voltage to output a comparison result signal indicating the comparison result; an on-time adjusting circuit to adjust on-time (length of time on) and off-time (length of time off) of the switching elements based on the comparison result signal, and output either a high control signal or a low control signal based on the adjusting result to feed back to the second feedback circuit; and a driver circuit to control the switching elements so that when the control signal is low, the first switching element is switched on and the second switching element is switched off, and when the control signal is high, the first switching element is switched off and the second switching element is switched on, wherein the second feedback circuit operates in accordance with the control signal from the first comparator, and generates the second feedback voltage based on a difference between the input voltage and the output voltage of the DC-DC converter when the control signal is low and generates the second feedback voltage based on the output voltage of the DC-DC converter when the control signal is high.