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Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package

Drive a String of 2 to 6 WLEDs for 1.5in to 4in LCD Backlighting Used in Battery Operated Devices

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • Cost-Effective and Flexible Solution for Wide Range of Backlighting Applications
    • Supplies from 2 to 6 WLEDs with 1.3% LED Current Accuracy
    • 2.6V to 5.5V Input Voltage Range
    • Fixed-Frequency Operation
    • Flexible Dimming Control
    • Direct PWM Dimming (MAX8901A)
    • 32-Step, Single-Wire Serial Dimming (MAX8901B)
  • Protection Features Improve System Reliability
    • WLED Overvoltage Protection (25V typ)
    • Internal Soft-Start and Thermal Shutdown
    • Input Undervoltage Lockout
    • Input Overvoltage Lockout
  • High Efficiency Extends Battery Life
    • Up to 91% Efficiency
    • 0.01µA (typ) Shutdown Current
    • No WLED Current in Shutdown
  • 8-Pin, 2mm x 2mm TDFN Package Saves Space

Applications/Uses

  • Cellular Phones
  • Digital Cameras
  • Display Backlight (from 2 to 6 WLEDs)
  • MP3 and Portable Media Players
  • PDAs and Smartphones
  • Portable Navigation Devices

Description

The MAX8901A/MAX8901B step-up converters drive from two to six series-connected white LEDs (WLEDs) with constant current to provide uniform WLED intensity for LCD backlighting in cell phones, PDAs, and other handheld devices. The MAX8901_ operate at a fixed 750kHz (typ) switching frequency, allowing for tiny external components, and are optimized for the highest possible efficiency over the full 1-cell Li+/Li-Poly battery range.

These converters use a single input (ON) to enable the IC and to control WLED intensity. The MAX8901A requires a direct PWM input to regulate WLED intensity with the WLED current proportional to the PWM duty cycle. The MAX8901B uses single-wire, serial-pulse dimming that reduces the WLED intensity in 32 linear steps. Full-scale WLED current for serial-pulse dimming is 24.75mA (MAX8901B, 0.75mA/step).

The MAX8901_ feature an internal soft-start to eliminate inrush currents during startup, input overvoltage protection, WLED overvoltage protection, and a shutdown mode with 0.01µA (typ) shutdown current. No WLED current is present in shutdown provided the WLED forward voltage is greater than the input supply voltage. Additional features include undervoltage lockout (UVLO) and thermal shutdown.

The MAX8901_ are available in tiny 8-pin, 2mm x 2mm TDFN-EP packages (0.8mm max height).

Simplified Block Diagram

MAX8901A, MAX8901B: Typical Operating Circuits MAX8901A, MAX8901B: Typical Operating Circuits 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.