Floating output voltage boost regulator driving LEDs using a buck controller

Patent metadata

Field	Value
Publication number	US-9078317-B1
Application number	US-201414332830-A
Country	US
Kind code	B1
Filing date	Jul 16, 2014
Priority date	Apr 4, 2014
Publication date	Jul 7, 2015
Grant date	Jul 7, 2015

Abstract

An LED driver uses a positive-to-floating boost converter topology to generate a negative voltage −Vee relative to ground. The converter receives an input voltage. Vin from a power supply. One end of an output inductor is coupled to ground, and the other end of the inductor is coupled between a highside switch and a low side switch. The bottom terminal of the lowside switch generates −Vee. The anode end of an LED string is coupled to Vin and the cathode end is coupled to −Vee. The converter detects the LED current and regulates the switching duty cycle so that the LED current is equal to a target current. This is more efficient than coupling the anode end of an LED string to ground and the cathode end to −Vee. A conventional buck controller IC may be used.

First claim

What is claimed is:

1. A current regulator system for driving a string of light emitting diodes (LEDs) with a regulated current comprising:
a first switch having a first terminal coupled to receive a positive input voltage Vin, relative to ground, from a power supply, the first switch having a second terminal coupled to a first end of an inductor;
a rectifier having a first terminal coupled to the second terminal of the first switch, the rectifier having a second terminal output…

Assignees

• Linear Techn Inc

Inventors

• Szolusha Keith D

Classifications

• H05B33/0815 Primary

  Electricity · mapped topic

• H05B45/375

  Electricity · mapped topic

• H05B45/38 Primary

  Electricity · mapped topic

• H05B45/39

  Electricity · mapped topic