Driving LEDs in LCD backlight

摘要

A backlight driver includes current sources that are connected between LED strings and a number of bias voltages. There can be any number of different bias voltages, each at a ground potential or higher voltage. The bias voltage is selected for a particular LED string in order to reduce a current drop across the current source. This reduces the power consumption of the current source and LED string. Heat dissipation is also reduced.

主权项

1. A system comprising:
a first voltage input, second voltage input, and third voltage input; a first voltage generator circuit, coupled to the first voltage input and generating a first voltage output, wherein the first voltage output is at a higher voltage level than the first voltage input; a first current source block comprising a first current source node, coupled to a first plurality of light emitting diodes; a second current source block comprising a second current source node, coupled to a second plurality of light emitting diodes; a first multiplexing block coupled to the second and third voltage inputs, and a first multiplexing block output is coupled to the first current source block; and a second multiplexing block coupled to the second and third voltage inputs, and a second multiplexing block output is coupled to the second current source block, wherein the first voltage output and the first current source node are configured to be coupled to the first plurality of light emitting diodes, and the first voltage output and the second current source node are configured to be coupled to the second plurality of light emitting diodes.