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US 12,677,361 B2Granted
Transformer-based light-source driving systems
AssigneeO2Micro, Inc.
InventorsKaiping Ran, Sheng-Tai Lee, Weiwei Song
Life of this patent
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Abstract
A light-source driving system includes a first controller, a switch circuit, and a second controller. The first controller is configured to control power transferred from a primary winding of a transformer to a first secondary winding and a second secondary winding of the transformer according to a load of a system circuit powered by the second secondary winding. The switch circuit is configured to enable the first secondary winding to provide a portion of the transferred power to a light source when the switch circuit is turned on. The second controller is coupled to the switch circuit and the first controller and is configured to monitor a status of the light source and control the switch circuit according to the status.
Claims17
A light-source driving system comprising:
- a first controller configured to control power transferred from a primary winding of a transformer to a first secondary winding and a second secondary winding of said transformer according to a load of a system circuit powered by said second secondary winding;
- a switch circuit configured to enable said first secondary winding to provide a portion of said power to a light source when said switch circuit is turned on;
- and
- a second controller, coupled to said switch circuit and said first controller, and configured to monitor a status of said light source and control said switch circuit according to said status,
- wherein said second controller comprises:
- a driving terminal configured to provide a driving signal to control said switch circuit;
- and
- a synchronizing terminal configured to detect an electrical polarity of an output terminal of said second secondary winding, wherein said second controller is configured to generate said driving signal according to said status when a positive polarity is detected at said synchronizing terminal, and configured to pause generating said driving signal when said positive polarity is not detected at said synchronizing terminal.
5 more elements
A light-source driving system comprising:
- a first controller configured to control power transferred from a primary winding of a transformer to a first secondary winding and a second secondary winding of said transformer according to a load of a system circuit powered by said second secondary winding;
- a switch circuit configured to enable said first secondary winding to provide a portion of said power to a light source when said switch circuit is turned on;
- and
- a second controller, coupled to said switch circuit and said first controller, and configured to monitor a status of said light source and control said switch circuit according to said status,
- wherein said second controller comprises:
- a monitoring terminal configured to monitor said status of said light source;
- and
- an adjusting terminal configured to receive an adjusting signal indicating a target level of a current through said light source, wherein said second controller is configured to adjust said current to said target level when said status of said light source indicates that said light source is in a normal-power state.
5 more elements
A method for controlling a light source, comprising:
- controlling power transferred from a primary winding of a transformer to a first secondary winding and a second secondary winding of said transformer according to a load of a system circuit powered by said second secondary winding;
- enabling said first secondary winding to provide a portion of said power to a light source by turning on a switch circuit coupled to said first secondary winding and said light source;
- monitoring a status of said light source;
- controlling, using a controller coupled to said switch circuit and said light source, said switch circuit according to said status;
- receive an adjusting signal, at an adjusting terminal of said controller, indicating a target level of a current through said light source;
- adjusting said current through said light source to said target level when said status of said light source indicates that said light source is in a normal-power state;
- monitoring said status of said light source by sensing a voltage level at a negative terminal of an LED (light-emitting diode) string in said light source, wherein said negative terminal is coupled to a reference ground through a transistor and a resistor;
- receiving a PWM (pulse with modulation) signal at said adjusting terminal;
- converting a duty cycle of said PWM signal to an adjusting voltage;
- and
- applying said adjusting voltage to said resistor by controlling said transistor such that a current through said LED string is adjusted to said target level.
8 more elements
A light source controller comprising:
- a monitoring terminal configured to monitor a status of a light source that is powered by a first secondary winding of a transformer comprising a primary winding, said first secondary winding, and a second secondary winding;
- a driving terminal configured to provide a driving signal to control a switch circuit that, when said switch circuit is turned on, enables said first secondary winding to provide said light source with a portion of power transferred from said primary winding to said first and second secondary windings;
- a synchronizing terminal configured to detect an electrical polarity of an output terminal of said second secondary winding;
- and
- control circuitry, coupled to said monitoring terminal, said driving terminal, and said synchronizing terminal, configured to generate said driving signal according to said status of said light source when a positive polarity is detected at said synchronizing terminal, and configured to pause generating said driving signal when said positive polarity is not detected at said synchronizing.
2 more elements
Dependencies are inferred from the claim text.