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High-Efficiency CCFL Backlight Controller with SMBus Interface

Integrated Backlight Controllers Optimized to Drive CCFLs Using a Resonant Full-Bridge Inverter Architecture

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • Synchronized to Resonant Frequency
    • Longer Lamp Life
    • Guaranteed Striking Capability
    • High Power-to-Light Efficiency
  • Wide Input Voltage Range (4.6V to 28V)
  • Feed Forward for Excellent Line Rejection
  • SMBus Dimming Control Interface
  • 10:1 Dimming Range
  • Guaranteed 200Hz to 220Hz DPWM Frequency
  • Secondary Voltage Limit Reduces Transformer Stress
  • Adjustable Lamp-Out Protection with 1s Timer
  • Secondary Current Limit Protects Against High-Voltage Short Circuits to Ground
  • Small, 5mm x 5mm, Thin QFN Package

Applications/Uses

  • LCD Monitors
  • LCD TVs
  • Notebook Computer Displays

Description

The MAX8709B integrated backlight controller is optimized to drive cold-cathode fluorescent lamps (CCFLs) using a resonant full-bridge inverter architecture. The resonant operation maximizes striking capability and provides near-sinusoidal waveforms over the entire input range to improve CCFL lifetime. The controller operates over a wide input voltage range of 4.6V to 28V with high power-to-light efficiency. The device also includes safety features that effectively protect against many single-point fault conditions including lamp-out and short-circuit faults.

The MAX8709B achieves 10:1 dimming range by “chopping” the lamp current on and off using a digital pulse-width-modulation (DPWM) method. The minimum DPWM duty cycle of the MAX8709B is 12.5%. The brightness is controlled with a 2-wire SMBus™-compatible interface. The device directly drives the four external N-channel power MOSFETs of the full-bridge inverter. An internal 5.3V linear regulator powers the MOSFET drivers, the DPWM oscillator, and most of the internal circuitry. The MAX8709B is available in a space-saving 28-pin thin QFN package and operates over a -40°C to +85°C temperature range.

Simplified Block Diagram

MAX8709B: Typical Operating Circuit MAX8709B: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.