Patent ID: 8587268

Claim:
A buck regulator circuit for providing buck regulation to supply a regulated load current to a load, the buck regulator circuit operable with a buck inductor coupled to the buck regulator at a switch node and to the load at an output node, the buck regulator circuit comprising: a switcher circuit operable to provide buck regulation and supply an inductor current through the buck inductor to the load; and an analog bypass (ACB) circuit including: an ACB current source coupled to the output node and in parallel with the buck inductor, and configured to supply, in response to an ACB control signal, an ACB current to the load; and an ACB control circuit configured to provide the ACB control signal; wherein the switcher circuit and the buck inductor are characterized by a switcher/inductor drop out resistance, and the ACB current source is characterized by an ACB resistance, such that a regulator drop out resistance at the output node corresponds to the switcher/inductor drop out resistance in parallel with the ACB resistance, which is less than the switcher/inductor drop out resistance; and wherein the ACB control circuit includes: a current comparator circuit configured to receive inductor current information from the switcher circuit, and to provide an inductor current signal representative of the inductor current relative to a predetermined current limit of the inductor; and a drop out detector circuit configured to receive drop out information from the switcher circuit, and to provide a drop out signal representative of buck regulation operation of the switcher circuit relative to a predetermined drop out condition in which the switcher substantially ceases regulation; wherein the ACB control circuit is operable to provide the ACB control signal based on the inductor current signal and the drop out signal.