Patent ID: 8643354

Claim:
A multi-phase switching regulator, comprising: a first phase power stage switching at least one first power transistor according to a first phase pulse width modulation (PWM) signal; at least one second phase power stage respectively switching at least one corresponding second power transistor of the second phase power stage according to a second PWM signal and converting an input voltage to an output voltage together with the first phase power stage; a feedback circuit generating a feedback signal according to the output voltage; a first phase PWM controller generating the first phase PWM signal according to the feedback signal and adjusting the first phase PWM signal according to a current balance signal; at least one second phase PWM controller generating the at least one second phase PWM signal according to the feedback signal, adjusting the at least one second phase PWM signal according to the current balance signal, and receiving a phase adjustment signal to determinate the number of the second phase power stages which are active or inactive; and a current balance circuit generating the current balance signal according to a first signal related to a current outputted by the first phase power stage and at least one second signal related to a current outputted by the at least one second phase power stage, wherein during a transition of phase adjustment, the current balance circuit is inactivated or its gain is reduced according to the phase adjustment signal, thereby avoiding an undershoot in the output voltage.