LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHT SOURCE

摘要

A load control device for controlling the amount of power delivered to an electrical load is able to operate in a burst mode to adjust the amount of power delivered to the electrical load to low levels. The load control device comprises a control circuit that operates in a normal mode to regulate an average magnitude of a load current conducted through the load to a target load current that ranges from a maximum rated current to a minimum rated current. The control circuit operates in the burst mode to regulate the average magnitude of the load current below the minimum rated current. During the burst mode, the control circuit regulates a peak magnitude of the load current to the minimum rated current during a first time period, and stops regulating the load current during a second time period, such that the average magnitude of the load current is below the minimum rated current.

主权项

1. An LED driver for controlling an intensity of an LED light source, the LED driver comprising:
an LED drive circuit configured to conduct a load current through the LED light source and to control the intensity of the LED light source; a current sense circuit configured to provide a load current feedback signal that indicates a magnitude of the load current; and a control circuit configured to generate at least one drive signal for controlling the LED drive circuit to adjust an average magnitude of the load current, the control circuit configured to adjust an operational characteristic of the at least one drive signal in response to the load current feedback signal in order to control the intensity of the LED light source towards a target intensity, wherein the control circuit is configured to operate in a normal mode to regulate the average magnitude of the load current towards a target load current that ranges from a maximum rated current to a minimum rated current, the control circuit further configured to operate in a burst mode to regulate the average magnitude of the load current below the minimum rated current; wherein, during the burst mode, the control circuit is configured to control the LED drive circuit in an active state during a first time period in which the control circuit adjusts the operational characteristic of the at least one drive signal to regulate a peak magnitude of the load current towards approximately the minimum rated current in response to the load current feedback signal, the control circuit further configured to control the LED drive circuit in an inactive state during a second time period in which the control circuit stops generating the at least one drive signal and maintains the operational characteristic of the at least one drive signal constant, such that the average magnitude of the load current is less than the minimum rated current.