Patent ID: 7148670

Claim:
A dual made regulator comprising: a switching regulator portion for controlling a duty cycle of a switch to regulate a voltage at an output terminal, the switching regulator portion being controlled to regulate the voltage at the output terminal for load currents exceeding a certain threshold, the switching regulator portion including a first error amplifier receiving a first reference voltage and a voltage feedback signal; a linear regulator portion for controlling a series transistor coupled between an input voltage and the output terminal, the linear regulator portion being controlled to regulate the voltage at the output terminal for load currents below a certain threshold, the linear regulator including a second error amplifier receiving a second reference voltage and a voltage feedback signal, the linear regulator portion including at least one bias generator for generating a bias signal wherein increasing a magnitude of the bias signal shortens a response time of the linear regulator when reacting to a change in voltage at the output terminal; transition circuitry coupled to the switching regulator portion and the linear regulator portion for operating during a transition between a switching regulator mode and a linear regulator mode, the transition circuitry comprising: control circuitry for temporarily raising the first reference voltage during a transition from a linear regulator mode to a switching regulator made, for temporarily raising the second reference voltage during a transition from the switching regulator mode to the linear regulator mode, for temporarily raising the bias signal during a transition from the linear regulator mode to the switching regulator mode and during a transition from the switching regulator mode to the linear regulator mode, and for temporarily augmenting the series transistor for increasing a current handling capacity of the linear regulator portion during a transition from the linear regulator mode to the switching regulator mode and during a transition from the switching regulator mode to the linear regulator mode.