System and method for providing an active current assist with analog bypass for a switcher circuit
First Claim
1. 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.
1 Assignment
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Accused Products
Abstract
A system and method are disclosed for providing an active current assist with analog bypass for a switcher circuit. An active current assist circuit is coupled to a buck regulator circuit, which includes a switcher circuit, an inductor circuit and a capacitor circuit. The active current assist circuit includes an active current analog bypass control circuit and a current source. The active current analog bypass control circuit receives and uses current limit information, voltage error information, and drop out information to determine a value of assist current that is appropriate for a current operational state of the buck regulator circuit. The active current analog bypass control circuit causes the current source to provide the appropriate value of assist current to the buck regulator circuit.
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Citations
28 Claims
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1. 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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. 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:
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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; wherein the ACB current source includes series coupled pull-up and pull-down digital to analog converters (DACs) responsive to polarity select signals to selectively enable either the pull-up DAC to source the ACB current to the output node, or the pull-down DAC to sink the ACB current from the output node; 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; 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; a combination logic and state machine configured to provide, in response to the inductor current signal and the drop out signal, (i) a variable multi-bit control value, and (ii) the polarity select signals; and a DAC count circuit configured to provide, in response to the variable multi-bit count value, the ACB control signal to control the pull-up and pull-down DACs. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of buck regulation to supply a regulated load current to a load through a buck inductor that is coupled to a buck regulator at a switch node and to the load at an output node, the method of buck regulation comprising:
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operating the buck regulator to supply an inductor current through the buck inductor to the load; and controlling an ACB current source coupled to the output node in parallel with the buck inductor to supply at the output node an ACB current to the load; wherein the buck regulator 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 providing an ACB control signal to control the ACB current source by; providing, in response to inductor current information, an inductor current signal representative of the inductor current relative to a predetermined current limit of the inductor; and providing, in response to drop out information, a drop out signal representative of buck regulation relative to a predetermined drop out condition in which buck regulation substantially ceases; providing the ACB control signal based on the inductor current signal and the drop out signal. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification