A multi-phase switch mode, voltage regulator has a transient mode portion in which a phase control output is coupled to one or more control inputs of one or more switch circuits that conduct inductor current through one or more transient phase inductors, from amongst a number of phase inductors. A slew mode control circuit detects a high slope and then a low slope in the feedback voltage and, in between detection of the high slope and the low slope, pulses the phase control output of the transient mode portion so that the switch circuit that conducts transient phase inductor current adds power to, or sinks power from, the power supply output. Other embodiments are also described.