Light-emitting diode (LED) driver and controller
AssigneeMarvell World Trade Ltd.
InventorsWanfeng Zhang, Jianqing Lin, Shaoan Dai
Life of this patent
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Abstract
Apparatuses, methods, systems, and circuits for light-emitting diode (LED) control are disclosed. In one embodiment, an LED control circuit can include a first pin receiving an input voltage supply; a second pin receiving a primary signal from a primary winding of a transformer coupled to the LED; a third pin coupled to a ground supply; and logic configured to estimate an output current and/or output voltage at the LED coupled to a secondary winding of the transformer from the input voltage supply and the primary signal.
Claims18
A light-emitting diode (LED) control circuit, the LED control circuit comprising:
- a first input configured to receive an input voltage supply;
- a second input configured to receive a primary signal from a primary winding of a transformer coupled to said LED;
- and
- logic configured to estimate an output current and/or voltage at said LED coupled to a secondary winding of said transformer from said input voltage supply and said primary signal, wherein said primary signal includes a primary voltage and a primary current of said transformer, wherein said logic comprises an output voltage estimator configured to estimate said output voltage from said input voltage supply and said primary voltage;
- and
- an output current estimator configured to receive said primary current and to estimate said output current from said primary current when a switch coupled to said second input is on.
A method of controlling a light-emitting diode (LED), the method comprising:
- determining if a current is passing through a secondary winding of a transformer by comparing a threshold voltage and a primary voltage at a primary winding of the transformer;
- estimating an output current through said LED from a current through said primary winding when a switch coupled to said secondary winding is on;
- and
- counting a number of clock cycles that said secondary side winding has a non-zero current, and estimating an output voltage at said LED or at a secondary winding of said transformer using said primary voltage when said switch is off.
An apparatus for controlling a light-emitting diode (LED), the apparatus comprising:
- a transformer having a primary winding and a secondary winding, wherein said secondary winding is coupled to said LED;
- and
- a controller having a first input coupled to an input voltage supply and a first terminal of said primary winding, and a second input coupled to a second terminal of said primary winding, wherein said controller is configured to estimate an output voltage and an output current provided from said secondary winding to said LED from said input voltage supply, a primary voltage at a terminal of said primary winding, and a primary current at said second input, and provide an LED control signal from said estimated output voltage and said estimated output current.
Dependencies are inferred from the claim text.