A first light source illuminates a first region. A second light source is configured to provide lower luminance than that of the first light source. The second light source illuminates a second region that overlaps the first region, and that has a larger area than that of the first region. A lighting circuit drives the first light source and the second light source according to a common lighting instruction. The lighting circuit gradually turns on the first light source and the second light source with different gradual changing time periods in response to the lighting instruction.

In accordance with an embodiment, a method of operating a switch-mode power supply includes receiving a measurement of a first current of the switch-mode power supply, determining a ripple of the first current based on the received measurement of the first current, determining a maximum current threshold based on a target average current and the determined ripple of the first current, determining an off time of a switch based on a target current ripple and the determined ripple of the first current, turning off the switch when the first current reaches the maximum current threshold, and turning on the switch after the determined off time has elapsed after turning off the switch.

A switched power converter (102) is arranged for supplying lighting means (108) as a load, having at least one (M40, M41) switch controlled by a control unit (106), wherein the control unit (106) comprises: a feedback controller, such as an ASIC or microcontroller, generating a switch control signal based on a feedback signal (Imeas), such as e.g. the load current (ILED), and
a separate sweep block, supplied with a signal representing a characteristic of the load (LED), such as e.g. the load voltage (VLED), and modulating the switch control signal (tout-ctrl) by a cyclic sweep, wherein the modulated switch control signal (tout-sweep) is provided directly or indirectly to the at least one switch (M40, M41).

A switched power converter (102) is arranged for supplying lighting means (108) as a load, having at least one (M40, M41) switch controlled by a control unit (106), wherein the control unit (106) comprises: a feedback controller, such as an ASIC or microcontroller, generating a switch control signal based on a feedback signal (Imeas), such as e.g. the load current (ILED), and
a separate sweep block, supplied with a signal representing a characteristic of the load (LED), such as e.g. the load voltage (VLED), and modulating the switch control signal (tout-ctrl) by a cyclic sweep, wherein the modulated switch control signal (tout-sweep) is provided directly or indirectly to the at least one switch (M40, M41).

A method for controlling an amount of power delivered to an electrical load may include controlling an average magnitude of a load current towards a target load current that ranges from a maximum-rated current to a minimum-rated current in a normal mode, and controlling the average magnitude of the load current below the minimum-rated current in a burst mode. The burst mode may include at least one burst-mode period that comprises a first time period associated with an active state and a second time period associated with an inactive state. During the burst mode, the method may include regulating a peak magnitude of the load current towards the minimum-rated current during the active state, and stopping the generation of at least one drive signal during the inactive state to control the average magnitude of the load current to be less than the minimum-rated current.

A method for controlling an amount of power delivered to an electrical load may include controlling an average magnitude of a load current towards a target load current that ranges from a maximum-rated current to a minimum-rated current in a normal mode, and controlling the average magnitude of the load current below the minimum-rated current in a burst mode. The burst mode may include at least one burst-mode period that comprises a first time period associated with an active state and a second time period associated with an inactive state. During the burst mode, the method may include regulating a peak magnitude of the load current towards the minimum-rated current during the active state, and stopping the generation of at least one drive signal during the inactive state to control the average magnitude of the load current to be less than the minimum-rated current.

The present invention includes self-contained, rechargeable power systems for areas having unreliable electrical grids or no electrical grid at all, and methods related thereto. The system may include one or more solar panels of various sizes to provide an off-grid power generation source, battery receivers for receiving batteries of various chemistries, and a control circuitry that is operable to detect the voltage and/or current output of the batteries that are installed in the system to determine their specific battery chemistry and then adjust the charge algorithm of the batteries to optimize both the charge capacity and the cycle life of the batteries. The control circuitry may also be operable to switch configurations of the solar panels and/or the batteries to optimize performance of the system. The system may be operable to power one or more light emitters and/or external electronic devices connected through the system by a charge port.

The present invention includes self-contained, rechargeable power systems for areas having unreliable electrical grids or no electrical grid at all, and methods related thereto. The system may include one or more solar panels of various sizes to provide an off-grid power generation source, battery receivers for receiving batteries of various chemistries, and a control circuitry that is operable to detect the voltage and/or current output of the batteries that are installed in the system to determine their specific battery chemistry and then adjust the charge algorithm of the batteries to optimize both the charge capacity and the cycle life of the batteries. The control circuitry may also be operable to switch configurations of the solar panels and/or the batteries to optimize performance of the system. The system may be operable to power one or more light emitters and/or external electronic devices connected through the system by a charge port.

The invention provides an LED drive power supply and a controller thereof. The controller comprises a ground terminal, a sampling terminal, and a power supply terminal. The ground terminal and an output ground of a power supply module have different potentials. A drain of a power switching transistor is coupled to a positive output terminal of the power supply module, a source of the power switching transistor and the sampling terminal are coupled to a first terminal of a sampling resistor, and a second terminal of the sampling resistor is coupled to the ground terminal. The controller further includes a logic control circuit determining whether a sampling voltage input by the sampling terminal is zero; a driver generating a first driving signal to the power switching transistor; and a bias circuit configured to receive a power supply voltage.

A deadtime control scheme for improving buck converter light load efficiency.