Multi-stage power supply for a load control device having a low-power mode

摘要

A multi-stage power supply for a load control device is able to operate in a low-power mode in which the power supply has a decreased power consumption when an electrical load controlled by the load control device is off. The load control device comprises a load control circuit and a controller, which operate to control the amount of power delivered to the load. The power supply comprises a first efficient power supply (e.g., a switching power supply) operable to generate a first DC supply voltage. The power supply further comprises a second inefficient power supply (e.g., a linear power supply) operable to receive the first DC supply voltage and to generate a second DC supply voltage for powering the controller. The controller controls the multi-stage power supply to the low-power mode when the electrical load is off, such that the magnitude of the first DC supply voltage decreases to a decreased magnitude and the inefficient power supply continues to generate the second DC supply voltage.

主权项

1. A load control device for controlling the amount of power delivered from a power source to an electrical load, the load control device comprising:
a load control circuit adapted to be coupled between the source and the load for controlling the power delivered to the load; a controller operatively coupled to the load control circuit and operable to control the load control circuit to turn the electrical load off; and a multi-stage power supply comprising a first efficient power supply operable to generate a first DC supply voltage output and a second inefficient power supply operable to receive the first DC supply voltage output and to generate a second DC supply voltage output for powering the controller, the first DC supply voltage output having a normal magnitude in a normal mode of operation; wherein the controller is coupled to the multi-stage power supply for controlling the multi-stage power supply to a low-power mode when the electrical load is off, such that the magnitude of the first DC supply voltage output decreases to a decreased magnitude that is less than the normal magnitude and greater than the magnitude of the second DC supply voltage output, and the second inefficient power supply continues to generate the second DC supply voltage output in the low-power mode when the electrical load is off and the magnitude of the first DC supply voltage output has decreased to the decreased magnitude.