Single inductor multiple output buck converter and control method thereof

A control circuit used in a single inductor multiple output buck converter, wherein the single inductor multiple output buck converter comprises an inductor having a first terminal and a second terminal, a first switch coupled between an input voltage and the first terminal of the inductor, a second switch coupled between the first terminal of the inductor and a reference ground, a third switch coupled between the second terminal of the inductor and a first output voltage, a fourth switch coupled between the second terminal of the inductor and a second output voltage, a first capacitor coupled between the first output voltage and the reference ground, and a second capacitor coupled between the second output voltage and the reference ground, and wherein the control circuit comprises:

• a first comparing circuit having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is configured to receive a first feedback signal indicative of the first output voltage, the second input terminal is configured to receive a first reference signal, and wherein the first comparing circuit compares the first feedback signal with the first reference signal and generates a first comparison signal at the output terminal;
• a second comparing circuit having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal is configured to receive a second feedback signal indicative of the second output voltage, the second input terminal is configured to receive a second reference signal, and wherein the second comparing circuit compares the second feedback signal with the second reference signal and generates a second comparison signal at the output terminal;
• and
• a logic circuit coupled to the output terminals of the first comparing circuit and the second comparing circuit, wherein the logic circuit detects which one of the first comparison signal and the second comparison signal is asserted first, and wherein based on the detection result, the logic circuit generates a first driving signal, a second driving signal, a third driving signal and a fourth driving signal to respectively control the first switch, second switch, third switch and fourth switch;
• wherein
• when the first comparison signal is asserted earlier than the second comparison signal, the logic circuit turns on the first switch and the third switch, turns off the second switch and the fourth switch, wherein the logic circuit will turn off the first switch and turn on the second switch once the on time of the first switch reaches a first time threshold;
• when the second comparison signal is asserted earlier than the first comparison signal, the logic circuit turns on the first switch and the fourth switch, turns off the second switch and the third switch, wherein the logic circuit will turn off the first switch and turn on the second switch once the on time of the first switch reaches a second time threshold.

A single inductor multiple output buck converter configured to provide a plurality of output voltage, comprising:

• an inductor having a first terminal and a second terminal;
• a first switch coupled between an input voltage and the first terminal of the inductor;
• a second switch coupled between the first terminal of the inductor and a reference ground;
• a plurality of output switches with each of the plurality of output switches coupled between the second terminal of the inductor and the corresponding output voltage;
• a plurality of output capacitors with each of the plurality of capacitors coupled between the corresponding output voltage and the reference ground;
• a plurality of feedback circuits generating a plurality of feedback signals, wherein each of the plurality of feedback circuits is configured to generate a corresponding feedback signal indicative of the corresponding output voltage;
• a plurality of comparing circuits generating a plurality of comparison signals, wherein each of the plurality of comparing circuits is configured to compare the corresponding feedback signal with a corresponding reference signal and generate a corresponding comparison signal;
• and
• a logic circuit coupled to the plurality of comparing circuits, wherein the logic circuit detects which one of the plurality of comparison signals is asserted first, and controls the first switch, second switch and the plurality of output switches based on the detection result.