Linear Technology AN65-1 LCD Backlight Application Note

About this manual

The document reviews recent work in components and measurement techniques applicable to LCD backlighting. It covers theoretical considerations with practical suggestions, remedies, and circuits designed to optimize efficiency and performance.

What's inside

• Introduction
• Perspectives on Display Efficiency
• Cold Cathode Fluorescent Lamps (CCFLs)
• CCFL Load Characteristics
• Display and Layout Losses
• Considerations for Multilamp Designs
• CCFL Power Supply Circuits
• Low Power CCFL Power Supplies
• High Power CCFL Power Supply
• Floating Lamp Circuits

Frequently asked questions

What is the primary goal of an efficient LCD backlight converter?

The converter should deliver the lamp drive in sine wave form to minimize RF emissions and provide optimal current-to-light conversion.

What percentage of battery drain is typically caused by CCFLs and their power supply?

The CCFL and its power supply are responsible for almost 50% of the battery drain in portable computers.

What is a common height restriction for LCD enclosures?

PCboard and all hardware usually must fit within the LCD enclosure with a height restriction of 0.25 inches.