Method And Apparatus To Control A DC-DC Converter
AssigneeAllegro MicroSystems, LLC
InventorsPranav Raval, Gregory Szczeszynski, Bassem Alnahas, Nai-Chi Lee
Life of this patent
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Abstract
Control circuits and techniques are provided for use with DC-DC converters. The circuits and techniques may, in some implementations, be used with LED driver systems. In some embodiments control circuits are provided that rely on multiple different feedback paths to adjust a duty cycle of a DC-DC converter. In some embodiments, control circuits are provided that switch between multiple capacitors to provide as duty cycle control signal for use with a DC-DC converter.
Claims41
An electronic circuit for use in driving a plurality of loads coupled to a common voltage node, each load in the plurality of loads including a series connected string of load devices, the electronic circuit comprising:
- a plurality of current regulators to regulate current through corresponding ones of the plurality of loads;
- and
- control circuitry to control a DC-DC converter to generate a regulated voltage on the common voltage node, the control circuitry comprising:
- a duty cycle control unit to control a duty cycle of the DC-DC converter, the duty cycle control unit being responsive to a duty cycle control signal at a control input thereof that is indicative of a duty cycle to be used by the duty cycle control unit;
- at least one capacitor to carry a voltage to act as the duty cycle control signal for the duty cycle control unit;
- and
- at least one error amplifier to facilitate adjustment of the voltage on the at least one capacitor based on feedback, the at least one error amplifier being configured to generate an error signal based, during first time periods, on the output voltage of the DC-DC converter and, during second time periods, on feedback from the plurality of current regulators, wherein the second time periods are different from the first time periods.
A method for operating a duty cycle control unit to generate a switching signal for a DC-DC converter, the DC-DC converter to generate an output voltage to power a plurality of light emitting diode (LED) channels coupled to a common voltage node, each LED channel in the plurality of LED channels including a series-connected string of LEDs, the duty cycle control unit having an input to receive a duty cycle control signal indicative of a duty cycle to be used for the DC-DC converter, the method comprising:
- generating an error signal for use in adjusting a voltage level on at least one capacitor coupled to the input of the duty cycle control unit based on feedback, wherein generating the error signal includes generating the error signal based on the output voltage of the DC-DC converter during first time periods and generating the error signal based on one or more voltages across one or more current regulators associated with the plurality of LED channels during second time periods, wherein the second time periods are different from the first time periods.
An electronic circuit for use in driving a plurality of loads coupled to a common voltage node, each load in the plurality of loads including a series-connected string of load devices, the electronic circuit comprising:
- control circuit for controlling a DC-DC converter to generate a regulated voltage on the common voltage node, the control circuitry comprising:
- a duty cycle control unit to control a duty cycle of the DC-DC converter, the duty cycle control unit being responsive to a duty cycle control signal, at a control input thereof that is indicative of a duty cycle to be used by the duty cycle control unit;
- a first capacitor to carry a first voltage to act as a duty cycle control signal for the duty cycle control unit;
- a second capacitor to carry a second voltage to act as a duty cycle control signal for the duty cycle control unit;
- and
- a switch circuit to alternately couple the first capacitor and the second capacitor to the control input of the duty cycle control unit in response to one or more control signals.
A method for operating a duty cycle control unit to generate a switching signal for a DC-DC converter, the duty cycle control unit having an input to receive a duty cycle control signal indicative of a duty cycle to be used for the DC-DC converter, the method comprising:
- alternately coupling at least a first capacitor and a second capacitor to the input of the duty cycle control unit, the first and second capacitors each having corresponding voltages across them that act as duty cycle control signals for the duty cycle control unit when the corresponding capacitors are coupled to the duty cycle control unit.
A control circuit for controlling a DC-DC converter to generate a regulated voltage, the control circuit comprising:
- a duty cycle control unit to control a duty cycle of the DC-DC converter, the duty cycle control unit being responsive to a duty cycle control signal at a control input thereof that is indicative of a duty cycle to be used by the duty cycle control unit;
- a first capacitor to carry a first voltage to act as a duty cycle control signal for the duty cycle control unit;
- a second capacitor to carry a second voltage to act as a duty cycle control signal for the duty cycle control unit;
- and
- a switch circuit to alternately couple the first capacitor and the second capacitor to the control input of the duty cycle control unit in response to one or more control signals.
Dependencies are inferred from the claim text.