Multi-phase SMPS with load transient control and associated control method

A control circuit, comprising:

• a feedback terminal configured to receive a feedback signal;
• a plurality of control signal output terminals;
• a plurality of comparing circuits, wherein each of the plurality of comparing circuits having a first input coupled to the feedback terminal, a second input coupled to a threshold voltage, and an output configured to provide a load indication signal;
• and
• a controller, comprising a plurality of inputs and a plurality of outputs, wherein each of the plurality of inputs is coupled to the output of the respective comparing circuit, each of the plurality of outputs is coupled to the respective control signal output terminal configured to provide a pulse width modulation (PWM) signal, and wherein the controller is configured to selectively set a plurality of the PWM signals in HIGH state according to the load indication signals.

A method of load transient control in a multi-phase SMPS, the multi-phase SMPS having an input coupled to a plurality of switches and having an output configured to provide an output voltage, wherein the SMPS comprises N switching circuits, the method comprising:

• comparing a feedback signal of the output voltage to a plurality of threshold voltages;
• judging the load condition of the multi-phase SMPS according to the comparison results, the comparison results obtained by:
• obtaining a plurality of load indication signals by comparing the feedback signal with a plurality of threshold voltages Vth1, Vth2 . . . Vthf, wherein Vth1>Vth2> . . . Vthf, and where f is a natural number from 2 to N;
• setting an index for each load indication signal, wherein the index is a natural number not higher than N, and wherein a load indication signal is in active state if the feedback signal is lower than a corresponding threshold voltage;
• finding a highest index of the load indication signals which are in active state;
• and
• simultaneously turning on the plurality of switches, wherein the number of the plurality of switches equals the highest index.