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High-Efficiency, Wide Brightness Range, CCFL Backlight Controllers

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • Synchronized-to-Resonant Frequency
    • Good Crest Factor for Longer Lamp Life
    • Ensures Maximum Strike Capability
  • High Power to Light Efficiency
  • Wide Dimming Range (3 Methods)
    • Lamp Current Adjust: >3 to 1
    • Digital PWM (DPWM): >10 to 1
    • Combined: >30 to 1
  • Feed-Forward for Fast Response to Step Change of Input Voltage
  • Wide Input Voltage Range (4.6V to 28V)
  • Transformer Secondary Voltage Limiting to Reduce Transformer Stress
  • Lamp-Out Protection with 2s Timeout
  • Short-Circuit and Other Single-Point Fault Protections
  • Synchronizable DPWM Frequency
  • Dual-Mode Brightness Control Interface
    • SMBus Serial Interface (MAX1895 Only)
    • Analog Interface (Both Devices)
  • High-Accuracy Analog Interface
    • Separate 100% Brightness Voltage Reference Pin (CRFSDA)
    • Separate Minimum Lamp-Current Set-Point Pin (MINDAC)
  • Small Footprint 28-Pin Thin QFN (5mm x 5mm) Package

Applications/Uses

  • Car-Navigation Displays
  • LCD Monitors
  • Notebook Computers
  • Point-of-Sale Terminals
  • Portable Display Electronics

Description

The MAX1895/MAX1995 integrated controllers are optimized to drive cold-cathode fluorescent lamps (CCFL) using a synchronized full-bridge inverter architecture. Synchronized drive provides near sinusoidal waveforms over the entire input range to maximize the life of CCFLs. The controllers also operate over a wide input voltage range with high efficiency and broad dimming range.

The MAX1895/MAX1995 include safety features that limit the transformer secondary voltage and protect against single-point fault conditions including lamp-out and short-circuit faults.

The MAX1895/MAX1995 regulate the CCFL brightness in three ways: linearly controlling the lamp current, digital pulse-width modulating (DPWM) the lamp current, or using both methods simultaneously to achieve the widest dimming range (>30:1). CCFL brightness can be controlled with either an analog voltage (both MAX1895 and MAX1995) or a two-wire SMBus™ compatible interface (MAX1895 only).

The MAX1895/MAX1995 directly drive the four external N-channel power MOSFETs of the full-bridge inverter. An internal 5.3V linear regulator powers the MOSFET drivers, the synchronizable DPWM oscillator, and most of the internal circuitry. The MAX1895/MAX1995 are available in the space-saving 28-pin thin QFN package and operate over the -40°C to +85°C temperature range.

Simplified Block Diagram

MAX1895, MAX1995: Functional Diagram MAX1895, MAX1995: Functional Diagram 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.