Boost and linear LED control
First Claim
1. A light emitting diode (LED) lighting subsystem, comprising:
- one or more LEDs;
a current source for the one or more LEDs, the current source including;
a transistor having a control input coupled to a constant voltage source, a first leg coupled to the one or more LEDs and a second leg; and
a current mirror coupled to the second leg of the transistor, the current mirror having a control node, a sense node indicative of an operating point of the LED lighting subsystem, and a transistor size ratio that determines an LED current provided to the one or more LEDs based on a control current received at the control node.
4 Assignments
0 Petitions
Accused Products
Abstract
A light emitting diode (LED) lighting system includes a switching power converter having an input for coupling to an alternating current (AC) power source, an output, and a switch. The LED lighting system also includes an LED lighting subsystem coupled to receive power from the output of the switching power converter. The LED lighting subsystem includes a current source for one or more LEDs, and the current source has a control node and a sense node. The LED lighting system additionally includes a switch state controller coupled to the switching power converter and coupled to the LED lighting subsystem. The switch state controller controls switching of the switch and varies a control current provided to the control node of the current source based on at least a parameter sensed from the sense node.
4 Citations
10 Claims
-
1. A light emitting diode (LED) lighting subsystem, comprising:
-
one or more LEDs; a current source for the one or more LEDs, the current source including; a transistor having a control input coupled to a constant voltage source, a first leg coupled to the one or more LEDs and a second leg; and a current mirror coupled to the second leg of the transistor, the current mirror having a control node, a sense node indicative of an operating point of the LED lighting subsystem, and a transistor size ratio that determines an LED current provided to the one or more LEDs based on a control current received at the control node. - View Dependent Claims (2, 3, 4, 5, 6)
-
- 7. A lighting system controller for a light emitting diode (LED) lighting system illuminating one or more LEDs from AC line voltage, wherein the lighting system controller receives a link voltage and a feedback signal indicative of an operating point of the LED lighting system, and responsive thereto, varies a control current provided to a current source that governs current through the one or more LEDs such that ripple in the one or more LEDs is no more than a predetermined amount.
Specification