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High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports

PWM-Capable Boost Maximizes Control and Efficiency for WLED Backlighting Applications

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • 28V Step-Up DC-DC Converter with Integrated nMOS Power Switch
    • Built-In 10-Bit PWM Control for Improved Efficiency
    • No Discharge Path During PWM Off Period for Increased Battery Life
    • Fixed 2MHz Switching for Smaller Components
    • Drives up to 6 Series WLEDs
  • ±8kV Human Body Model (HBM) ESD Protection for GPIOs and Boost-Converter Output
  • Five Open-Drain GPIOs Capable of Constant-Current LED Drive with Individual 8-Bit PWM Intensity Control
  • 2.7V to 5V Power-Supply Operation
  • Register Compatible with MAX6946/MAX6947 GPIO Port Expanders
  • 400kbps, 5.5V Tolerant I²C Interface
  • Four I²C Slave Address Choices
  • Active-Low RST Input Clears Serial Interface and Exits Shutdown (Reset-Run Option)
  • Small (2.31mm x 2.31mm) WLP Package

Applications/Uses

  • Cell Phones
  • Handheld Games
  • LED Backlighting for LCDs
  • PDAs
  • Portable Consumer Electronics

Description

The MAX6948B general-purpose input/output (GPIO) peripheral drives a series string of white LEDs (WLEDs), and contains up to five general-purpose input/output (GPIO) ports to drive additional LEDs.

The integrated 2MHz boost converter minimizes the size and cost of external components and supplies 30mA of load current at up to 28V. The converter is stable under all load conditions from 5V up to 28V and includes open-circuit detection to prevent damage to the IC. An I²C-programmable 10-bit pulse-width modulation (PWM) signal enables 1024 levels of WLED intensity.

The five GPIO ports function as logic inputs, open-drain logic outputs, or constant-current sinks in any combination. Ports withstand 5.5V independent of the MAX6948B's supply voltage. Two of the ports drive additional LEDs up to 30mA/port, while the other three ports drive LEDs at up to 10mA/port. The MAX6948B features shutdown and standby modes for low-power dissipation. The constant-current drivers contain programmable PWM outputs and allow staggering to reduce the input peak-current requirements. The I/O ports also feature ramp-up and ramp-down controls.

The MAX6948B features a single input to select from four I²C slave addresses. Programming and functionality for the five GPIO ports is identical to the MAX6946/MAX6947 I/O expanders.

The MAX6948B is available in a 25-bump (2.31mm x 2.31mm) WLP package for cell phones, PDAs, and other portable consumer electronic applications. The MAX6948B operates over the -40°C to +105°C temperature range.

Simplified Block Diagram

MAX6948B: Typical Operating Circuit MAX6948B: 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.