Patent ID: 9131567
Filing Date: 2015-09-08
Classification: H05B,Y02B

Abstract:
1. An apparatus comprising: an input node; a light-emitting diode (LED) string configured to receive a current from the input node, the LED string including a first portion and a second portion, each of the first and second portions including at least one LED; a voltage divider configured to output a control voltage and includes a first resistance element and a second resistance element coupled at an output node, the output node configured to output the control voltage, any one of or both of the first resistance element and the second resistance element having a temperature dependent characteristic; a node between the first and second portions of the LED string; and a switch configured to receive the control voltage output by the output node, the switch including a bipolar junction transistor (BJT) having a collector coupled to the node between the first and second portions of the LED string, an emitter directly coupled to a ground or the input node, and a base directly coupled to the output node, the switch configured to divert the current from the LED string according to the control voltage.