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Low-Cost CCFL Backlight Controller

High-Efficiency, IC-Optimized CCFL Controller for Portable Applications

Product Details

Key Features

Simplified Block Diagram

Technical Docs

Data Sheet Low-Cost CCFL Backlight Controller Mar 30, 2009

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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)
  • Input-Voltage Feed-Forward for Excellent Line Rejection
  • Accurate Dimming Control with Analog Interface
  • 10:1 Dimming Range
  • Adjustable Accurate DPWM Frequency with Sync Function
  • Adjustable Lamp Current Rise and Fall Time
  • Secondary Voltage Limit Reduces Transformer Stress
  • Lamp-Out Protection with Adjustable Timeout
  • Secondary Overcurrent Protection with Adjustable Timeout
  • Low-Cost, 24-Pin QSOP Package

Applications/Uses

  • LCD Monitors
  • LCD TVs
  • Notebook Computer Displays

Description

The MAX8722C integrated backlight controller is optimized to drive cold-cathode fluorescent lamps (CCFLs) using a full-bridge resonant inverter architecture. 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 (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 MAX8722C achieves 10:1 dimming range by "chopping" the lamp current on and off using a digital pulse-width modulation (DPWM) method. The DPWM frequency can be accurately adjusted with a resistor or synchronized to an external signal. The brightness is controlled by an analog voltage on the CNTL pin. The device directly drives the four external n-channel power MOSFETs of the full-bridge inverter. An internal 5.4V linear regulator powers the MOSFET drivers, the DPWM oscillator, and most of the internal circuitry. The MAX8722C is available in a low-cost, 24-pin QSOP package and operates over a -40°C to +85°C temperature range.

Simplified Block Diagram

MAX8722C: Typical Operating Circuit MAX8722C: Typical Operating Circuit Zoom icon

Technical Docs

Data Sheet Low-Cost CCFL Backlight Controller Mar 30, 2009

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 .