Multi-phase switching regulator and control circuit and control method thereof

A control circuit of a multi-phase switching regulator, the multi-phase switching regulator comprising:

• a plurality of power stages configured to operably convert an input voltage to an output voltage, wherein each power stage is one phase;
• wherein at least one of the power stages is configured to be enabled (phase-add) or disabled (phase-cut) according to a phase adjustment signal;
• and, wherein each power stage controls at least one power transistor in the corresponding power stage according to a corresponding pulse width modulation (PWM) signal, so that the plurality of power stages together convert the input voltage to the output voltage, while each phase generates a respective phase output current;
• the control circuit comprising:
• a plurality of PWM controllers, which are configured to operably generate the PWM signals for controlling the corresponding power stages according to an error signal which is related to an output voltage and a plurality of ramp signals corresponding to the plurality of PWM controller;
• and
• a ramp signal setting circuit, which is configured to operably adjust the ramp signal of the phase that is to be enabled or disabled according to the phase adjustment signal;
• wherein, under a phase-cut operation, the ramp signal setting circuit causes the ramp signal of the phase to be disabled to gradually change, such that a duty ratio of the PWM signal of the phase to be disabled gradually decreases.

A control method of a multi-phase switching regulator, wherein the multi-phase switching regulator comprises:

• a plurality of power stages configured to operably convert an input voltage to an output voltage, wherein each power stage is one phase;
• wherein at least one of the power stages is configured to be enabled (phase-add) or disabled (phase-cut) according to a phase adjustment signal;
• and, wherein each power stage controls at least one power transistor in the corresponding power stage according to a corresponding pulse width modulation (PWM) signal, so that the plurality of power stages together convert the input voltage to the output voltage, while each phase generates a respective phase output current;
• the control method comprising:
• generating the PWM signals according to an error signal which is related to an output voltage and a plurality of ramp signals corresponding to the plurality of power stages respectively;
• and
• adjusting the ramp signal of the phase that is to be enabled or disabled according to the phase adjustment signal;
• wherein, under a phase-cut operation, the ramp signal of the phase to be disabled is caused to gradually change, such that a duty ratio of the PWM signal of the phase to be disabled gradually decreases.