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High-Performance Negative Charge Pump for 6 White LEDs in 3mm x 3mm Thin QFN

Achieves Industry's Highest Efficiency Using a Negative Charge Pump to Independently Drive 6 White LEDs

Product Details

Key Features

Simplified Block Diagram

Technical Docs

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Key Features

  • Negative 1x/1.5x Charge Pump
  • Adaptive Current Regulators
  • Independent Voltage Supply for Each LED
  • 24mA to 0.1mA Serial-Pulse Dimming (MAX8847Y)
  • 24mA to 0mA PWM Dimming (MAX8847Z)
  • 2% (max) LED Current Accuracy, 1% (typ) Matching
  • Low 120µA Quiescent Current
  • Low 0.4µA Shutdown Current
  • Inrush Current Limit
  • Temperature Derating Function
  • 16-Pin, 3mm x 3mm Thin QFN Packages

Applications/Uses

  • Cellular Phones
  • PDAs, Digital Cameras, and Camcorders
  • White LED Backlighting

Description

The MAX8847Y/MAX8847Z negative charge pumps drive up to 6 white LEDs with regulated constant current for display backlight applications. By utilizing an inverting charge pump and extremely low-dropout adaptive current regulators, these ICs achieve very high efficiency over the full 1-cell Li+ battery voltage range even with large LED forward voltage mismatch. The 1MHz fixed-frequency switching allows for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple. The MAX8847Y/MAX8847Z include thermal shutdown, open- and short-circuit protection.

The MAX8847Y/MAX8847Z support independent LED on/off and dimming control. The MAX8847Z has PWM dimming control for LED1–LED6. The MAX8847Y has PWM dimming control for LED1–LED4 and serial-pulse dimming control for LED5 and LED6. The serial-pulse dimming ranges are pseudo-logarithmic from 24mA to 0.1mA and off in 32 steps. All devices include a temperature derating function to safely allow bright 24mA full-scale output current while automatically reducing current gradually to protect LEDs at high ambient temperatures above +60°C.

The MAX8847Y/MAX8847Z are available in 16-pin, 3mm x 3mm thin QFN packages.

Simplified Block Diagram

MAX8847Y, MAX8847Z: Typical Operating Circuit MAX8847Y, MAX8847Z: 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.