Multi-phase switching regulator and driver circuit and control method thereof
The present invention discloses a multi-phase switching regulator, a driver circuit of a multi-phase switching regulator, and a control method of a multi-phase switching regulator. The multi-phase switching regulator includes: at least two power stages, switching power transistors in the power stages to convert an input voltage to an output voltage according to pulse width modulation (PWM) signals generated by corresponding PWM controllers respectively; and a current balance circuit, generating a current balance signal according to the current of the corresponding power stage and a phase adjustment signal to averagely distribute current over the active power stages. In the present invention, the gain of the current balance circuit is adjustable, to avoid or reduce output voltage overshoot and undershoot when the phase number changes, while the current balance function is still achieved in normal operation.
1. 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.
2. The multi-phase switching regulator of claim 1 , wherein the gain is reduced to zero or approximate zero when the current balance circuit receives the phase adjustment signal.
3. The multi-phase switching regulator of claim 1 , wherein the first phase power stage and the second phase power stage are synchronous or asynchronous buck converters, boost converters, inverting converters, or buck-boost converters.
4. A driver circuit of a multi-phase switching regulator, the multi-phase switching regulator switching at least one power transistor of a first phase power stage and at least one power transistor of at least one second phase power stage according to a first pulse width modulation (PWM) signal and at least one second phase PWM signal, respectively, to convert an input voltage to an output voltage and generating a feedback signal according to the output voltage, the driver circuit comprising:
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.
5. The driver circuit of a multi-phase switching regulator of claim 4 , wherein the gain is reduced to zero or approximate zero when the current balance circuit receives the phase adjustment signal.
6. The driver circuit of a multi-phase switching regulator of claim 4 , wherein the first phase power stage and the second phase power stage are synchronous or asynchronous buck converters, boost converters, inverting converters, or buck-boost converters.
7. A control method of a multi-phase switching regulator, the multi-phase switching regulator switching at least one power transistor of a first phase power stage and at least one power transistor of at least one second phase power stage according to a first pulse width modulation (PWM) signal and at least one second phase PWM signal, respectively, to convert an input voltage to an output voltage and generating a feedback signal according to the output voltage, the control method comprising:
generating the first phase PWM signal according to the feedback signal and adjusting the first phase PWM signal according to a current balance signal;
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;
generating the at least one second phase PWM signal according to the feedback signal and adjusting the at least one second phase PWM signal according to the current balance signal;
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 the current balance signal has a gain;
receiving a phase adjustment signal to determinate the number of the second phase power stages which are active or inactive; and
stopping providing the current balance signal or reducing the gain of the current balance signal according to the phase adjustment signal during a transition of phase adjustment, thereby avoiding an undershoot in the output voltage.
8. The control method of a multi-phase switching regulator of claim 7 , wherein the first phase power stage and the second phase power stage are synchronous or asynchronous buck converters, boost converters, inverting converters, or buck-boost converters.
9. The control method of a multi-phase switching regulator of claim 7 , further comprising:
restoring the gain of the current balance circuit to a predetermined value after stopping providing the current balance signal or reducing the gain of the current balance signal for a predetermined period of time.