Active Transient Response for DC-DC Converters

A multi-phase DC-DC converter, comprising:

• a power stage including a plurality of phases, each phase having a high-side transistor and a low-side transistor for coupling to a load through a respective inductor;
• a pulse width modulator operable to switch the phases of the power stage via a variable duty cycle control signal for delivering current to the load through one or more of the inductors;
• and
• a transient response unit operable to switch the high-side transistors off and the low-side transistors off during a step-down event at the load if a measured inductor current in any of the inductors or collectively in all of the inductors exceeds a positive threshold value.

A method of operating a DC-DC converter including a first power transistor connected between a voltage supply node and a common node, a second power transistor connected between a reference node and the common node, and an inductor connected between the common node and the output node, the method comprising:

• switching the first and second transistors via a variable duty cycle control signal to deliver current to the load through the inductor;
• switching the first transistor off during a step-down event at the load;
• and
• switching the second transistor off during the step-down event irrespective of the state of the variable duty cycle control signal if current in the inductor exceeds a positive threshold value.