Converter with feedback voltage referenced to output voltage with separate ground planes for converter and load
AssigneeNational Semiconductor Corporation
InventorMichael J. Collins
Life of this patent
Estimating the term…
Abstract
A driver for a white LED string or a display is provided. The driver includes a boost converter that is arranged to provide an output voltage from a source voltage. Also, the driver includes a sense resistor that is coupled between the output voltage and a feedback voltage. The sense resistor is coupled in series with the white LED string or the display. Further, the boost converter uses the sense voltage across the sense resistor to regulate the output voltage. In one embodiment, the boost converter includes a level shifter that converts the sense voltage into a comparison signal that is referenced to ground. In another embodiment, the converter employs a reference voltage that is referenced to the output voltage.
Claims11
A circuit for driving a load, comprising:
- a first ground plane;
- a second ground plane that is separate from the first ground plane, wherein the load is coupled to the second ground plane, and wherein the load includes at least one of a white LED string and a display;
- a sense resistor circuit that is coupled between an output voltage node and a feedback voltage node such that the sense resistor circuit is coupled in series with the load, wherein the sense resistor is arranged to receive an output voltage at the output voltage node, and to provide the feedback voltage based on a load current through the load such that the feedback voltage is referenced to the output voltage;
- a boost converter that is arranged to regulate the output voltage based on the feedback voltage, wherein the first ground plane is local to the boost converter;
- and
- a level-shift circuit that is arranged to provide a comparison signal from the feedback voltage such that the comparison signal is referenced to ground.
A circuit for driving a load, comprising:
- a first ground plane;
- a second ground plane that is separate from the first ground plane, wherein the load is coupled to the second ground plane, and wherein the load includes at least one of a white LED string and a display;
- a sense resistor circuit that is coupled between an output voltage node and a feedback voltage node such that the sense resistor circuit is coupled in series with the load, wherein the sense resistor is arranged to receive an output voltage at the output voltage node, and to provide the feedback voltage based on a load current through the load such that the feedback voltage is referenced to the output voltage;
- and
- a boost converter that is arranged to regulate the output voltage based on the feedback voltage, wherein the first ground plane is local to the boost converter, and wherein the boost converter includes:
- a feedback circuit having at least a first input and a second input, wherein the feedback circuit is arranged to receive a reference signal at the first input, wherein the reference signal is referenced to the output voltage;
- to receive a feedback voltage at the second input;
- and to provide a control signal that is based, in part, on the reference signal and the comparison signal, wherein the feedback circuit includes at least one of an error amplifier and a comparator;
- a switch circuit;
- and
- a driver circuit that is arranged to drive the switch circuit based, in part, on the control signal such that the output voltage is regulated based, in part, on the control signal.
Dependencies are inferred from the claim text.