A high accuracy current-balanced control technique for LED backlight

Chia Lin Chiu*, Ke-Horng Chen

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

70 Scopus citations

Abstract

this paper proposes a new circuit to regulate current in parallel LED (Light Emitting Diodes) strings. The new technique not only enhances the current matching in each string but also reduces device numbers and external resistance requirements. In this new circuit, the LED current has a low correlation to its forward voltage (Vf). The LEDs should have constant driving current as LCD backlight for two reasons. Firstly, keeping the maximum current and maintain the reliability. Secondly, obtaining expected luminous intensity for each LED. Furthermore, this circuit matches the current of eight LED strings and keeps high accuracy by using only two operational amplifiers. In other words, it reduces the power consumption and die size. There are two benefits for having just one resistance outside. Firstly, it can reduce pin numbers of the driving circuit. Secondly, it is easy for user to determine the maximum current of LED strings instead of predefined by the driving IC. The current accuracy of LED strings with a total forward voltage variation (ΔV) around 1.1V is less than 0.1%.

Original languageEnglish
Title of host publicationPESC '08 - 39th IEEE Annual Power Electronics Specialists Conference - Proceedings
Pages4202-4206
Number of pages5
DOIs
StatePublished - 29 Sep 2008
EventPESC '08 - 39th IEEE Annual Power Electronics Specialists Conference - Rhodes, Greece
Duration: 15 Jun 200819 Jun 2008

Publication series

NamePESC Record - IEEE Annual Power Electronics Specialists Conference
ISSN (Print)0275-9306

Conference

ConferencePESC '08 - 39th IEEE Annual Power Electronics Specialists Conference
CountryGreece
CityRhodes
Period15/06/0819/06/08

Keywords

  • Current balance
  • Open-loop detection
  • PWM dimming

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