Two-terminal current controller and related LED lighting device

摘要

A two-terminal current controller controls a first current flowing through a parallel-coupled load. During a rising period of a rectified AC voltage, when a load voltage does not exceed a first voltage, the two-terminal current controller operates in a first mode. When the load voltage exceeds the first voltage but does not exceed a second voltage, the two-terminal current controller operates in a second mode. When the load voltage exceeds the second voltage, the two-terminal current controller operates in a third mode. When the load voltage drops to a third voltage smaller than the second voltage after exceeding the second voltage, the two-terminal current controller operates in the second mode when a difference between the second and third voltages exceeds a hysteresis band and operates in the third mode when a difference between the second and third voltages does not exceed the hysteresis band.

主权项

1. A two-terminal current controller for controlling a first current flowing through a load which is coupled in parallel with the two-terminal current controller, wherein:
during a rising period of a rectified AC voltage when a voltage established across the load does not exceed a first voltage, the two-terminal current controller operates in a first mode; during the rising period when the voltage established across the load exceeds the first voltage but does not exceed a second voltage, the two-terminal current controller operates in a second mode; and during the rising period when the voltage established across the load exceeds the second voltage, the two-terminal current controller operates in a third mode; during the rising period when the voltage established across the load drops to a third voltage smaller than the second voltage after exceeding the second voltage, the two-terminal current controller is configured to: operate in the second mode when a difference between the second and third voltages exceeds a first hysteresis band; and operate in the third mode when a difference between the second and third voltages does not exceed the first hysteresis band; the two-terminal current controller includes:
a current limiting unit configured to:
conduct a second current associated with the rectified AC voltage, regulate the second current according to the voltage established across the load and maintain the first current at zero when the two-terminal current controller operates in the first mode;conduct the second current, maintain the second current at a predetermined value larger than zero and maintain the first current at zero when the two-terminal current controller operates in the second mode; andswitch off when the two-terminal current controller operates in the third mode.