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US 7,999,487 B2Granted
Electronic circuit for driving a diode load with a predetermined average current
AssigneeAllegro MicroSystems, LLC
InventorGregory Szczeszynski
Life of this patent
Estimating the term…
Abstract
Electronic circuits and methods include provisions for passing a first current through a diode during a first time interval and for passing a second different current through the diode during a second different time interval. The first current is selected to achieve a predetermined voltage at a node of the diode. A duty cycle of the first current relative to the second current is selected to achieve a predetermined average current passing through the diode. In some arrangements, the diode is a light emitting diode.
Claims22
An electronic circuit, comprising:
- a current controlled circuit having a current sense output node at which a current sense signal is provided representative of a current flowing through the current controlled circuit, a voltage sense output node at which a voltage sense signal is provided representative of a voltage at the voltage sense output node, and a control node configured to receive a control signal to control the current flowing through the current controlled circuit;
- and
- a current/voltage control circuit having a current sense input node, a voltage sense input node, and an output node, wherein the current sense input node of the current/voltage control circuit is coupled to the current sense output node of the current controlled circuit, wherein the voltage sense input node of the current/voltage control circuit is coupled to the voltage sense output node of the current controlled circuit, wherein the output node of the current/voltage control circuit is coupled to the control node of the current controlled circuit, and wherein the current/voltage control circuit is configured to provide the control signal at the output node of the current/voltage control circuit resulting in a predetermined voltage at the voltage sense output node of the current controlled circuit and resulting in a predetermined average current passing through the current controlled circuit, the predetermined average current resulting by way of a feedback loop comprising the coupling between the current sense input node of the current/voltage control circuit and the current sense output node of the current controlled circuit.
An electronic circuit for lighting a light emitting diode having an anode and a cathode, the electronic circuit comprising:
- a current controlled circuit having a current sense output node at which a current sense signal is provided representative of a current flowing through the current controlled circuit, a voltage sense output node at which a voltage sense signal is provided representative of a voltage at the voltage sense output node, and a control node configured to receive a control signal to control the current flowing through the current controlled circuit, wherein the voltage sense output node of the current controlled circuit is configured to couple to a selected one of the anode or the cathode of the light emitting diode;
- a switching regulator having an input node, an output node, and a control node, wherein the output node of the switching regulator is configured to couple to a selected one of the anode of the light emitting diode or to the voltage sense output node of the current controlled circuit;
- and
- a current/voltage control circuit having a current sense input node, a voltage sense input node, and an output node, wherein the current sense input node of the current/voltage control circuit is coupled to the current sense output node of the current controlled circuit, wherein the voltage sense input node of the current/voltage control circuit is coupled to the voltage sense output node of the current controlled circuit, wherein the output node of the current/voltage control circuit is coupled to the control node of the current controlled circuit, and wherein the current/voltage control circuit is configured to provide the control signal at the output node of the current/voltage control circuit resulting in a predetermined voltage at the voltage sense output node of the current controlled circuit and resulting in a predetermined average current passing through the current controlled circuit, the predetermined average current resulting by way of a feedback loop comprising the coupling between the current sense input node of the current/voltage control circuit and the current sense output node of the current controlled circuit.
1 more element
A method for an LED driver circuit comprising a switching regulator, the method comprising:
- passing a first current through an LED and through a current controlled circuit having a current sense output node, a voltage sense output node, and a control node, wherein the first current is selected to result in a predetermined voltage at the voltage sense output node of the current controlled circuit;
- and
- alternating between the first current and a second different current passing through the LED and through the current controlled circuit in order to achieve a predetermined average current through the LED and through the current controlled circuit, the predetermined average current resulting by way of a feedback loop comprising the current sense output node.
Dependencies are inferred from the claim text.