A load short-circuit protection circuit of LED power supply includes a power supply end, a load end, a switching module disposed between the power supply end and the load end, and a sampling resistor set in series with the load end, and further includes a signal amplification module that collects the current change signal of the sample resistor, and a protection control module that receives a amplification signal of the signal amplification module and controls the on-off of the switching module according to the signal. The circuit can quickly magnify the subtle voltage difference changes on the sampling resistor and output them to the protection control module. The resistance value of the sampling resistance can be set very small to reduce the loss. Meanwhile, the selected devices are simple, with very fast response speed, low cost and high stability.

A driver circuit comprising an input inductor for receiving an input current provided to the driver circuit, and one or more switchable capacitors. Each switchable capacitor is switchable to connect in parallel across the input inductor and to disconnect from the input inductor, the input inductor and the switchable capacitors together thereby providing a variable impedance corresponding to the number of switchable capacitors are switched to connect to the input inductor, with the variable impedance variably limiting the input current. An associated method and an associated system are also provided.

A driver circuit comprising an input inductor for receiving an input current provided to the driver circuit, and one or more switchable capacitors. Each switchable capacitor is switchable to connect in parallel across the input inductor and to disconnect from the input inductor, the input inductor and the switchable capacitors together thereby providing a variable impedance corresponding to the number of switchable capacitors are switched to connect to the input inductor, with the variable impedance variably limiting the input current. An associated method and an associated system are also provided.

A circuit is provided for energy metering and surge current detection. It uses a current transformer. A first current sensing arrangement is connected to the secondary side of the transformer for energy metering and a second current sensing arrangement is connected to the secondary side, with a high pass filter, for surge current detection. A single component is thus able to provide energy metering and surge detection.

A circuit is provided for energy metering and surge current detection. It uses a current transformer. A first current sensing arrangement is connected to the secondary side of the transformer for energy metering and a second current sensing arrangement is connected to the secondary side, with a high pass filter, for surge current detection. A single component is thus able to provide energy metering and surge detection.

LED related lighting methods and apparatus are described. Various features relate to water tight light fixtures. Some of the fixtures are spotlights while other fixture are intended for in ground use. The light fixtures in at least some embodiments include power control features. In spotlight embodiments beam angle and power or light output can be controlled without opening the light assembly or compromising the water tight seals which also protect against dirt. In ground embodiments support tilt angle setting which allow a user to set the light fixture to one or more tilt angles. Beam angle can also be changed in some embodiments as well as power control. Beam angle, power control and tilt angle adjustments are supported in some embodiments but need not be supported in all embodiments with some embodiments using one or more of the described features but not all features.

Methods and apparatus for implementing a control apparatus for a light fixture for externally controlling the current to the LED light emitter of a landscape LED light fixture. In an exemplary embodiment a control apparatus for controlling current to an LED light source in a landscape lighting device includes an LED driver, a user control with a control setting indicator, and a driver housing including setting indicators.

A load short-circuit protection circuit of LED power supply includes a power supply end, a load end, a switching module disposed between the power supply end and the load end, and a sampling resistor set in series with the load end, and further includes a signal amplification module that collects the current change signal of the sample resistor, and a protection control module that receives a amplification signal of the signal amplification module and controls the on-off of the switching module according to the signal. The circuit can quickly magnify the subtle voltage difference changes on the sampling resistor and output them to the protection control module. The resistance value of the sampling resistance can be set very small to reduce the loss. Meanwhile, the selected devices are simple, with very fast response speed, low cost and high stability.

LED related lighting methods and apparatus are described. Various features relate to water tight light fixtures. Some of the fixtures are spotlights while other fixture are intended for in ground use. The light fixtures in at least some embodiments include power control features. In spotlight embodiments beam angle and power or light output can be controlled without opening the light assembly or compromising the water tight seals which also protect against dirt. In ground embodiments support tilt angle setting which allow a user to set the light fixture to one or more tilt angles. Beam angle can also be changed in some embodiments as well as power control. Beam angle, power control and tilt angle adjustments are supported in some embodiments but need not be supported in all embodiments with some embodiments using one or more of the described features but not all features.

This disclosure includes systems, methods, and techniques for controlling delivery of power to one or more strings of light-emitting diodes (LEDs). For example, a circuit includes a power converter configured to generate an electrical current, a switching device, and a sensor. The sensor is configured to compare a magnitude of the electrical current to a threshold, and in response to the magnitude exceeding the threshold, cause the switching device to turn on in order to sink a portion of the electrical current to prevent the magnitude of the electrical current from exceeding the threshold. When the switching device is turned on, the electrical current is divided into an undesired electrical current that flows across the switching device and a desired electrical current that flows to the string of LEDs.