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Adjustable-Output, Switch-Mode Current Sources with Synchronous Rectifier

High-Accuracy Current Sources Remain Cool While Fast Charging

Product Details

Key Features

Applications/Uses

Simplified Block Diagram

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Key Features

  • 95% Efficiency
  • +5.5V to +26V Input Supply Range
  • 2V to 24V Adjustable-Output Voltage Range
  • 100% Maximum Duty Cycle (Low Dropout)
  • Up to 500kHz PWM Operation
  • Optional Synchronous Rectifier
  • 16-Pin QSOP Package
  • Current-Sense Accuracy:
    • 2% (MAX1641)
    • 5.3% (MAX1640)

Applications/Uses

  • Backup Battery Charger
  • Battery-Powered Applications
  • Cell Phones
  • Cordless Phones
  • Handy Terminals
  • Laptop, Notebook, and Palmtop Computers
  • PCS Phones
  • Portable Consumer Products

Description

The MAX1640/MAX1641 CMOS, adjustable-output, switch-mode current sources operate from a +5.5V to +26V input, and are ideal for microprocessor-controlled battery chargers. Charging current, maximum output voltage, and pulse-trickle charge are programmed with external resistors. Programming the off-time modifies the switching frequency, suppressing undesirable harmonics in noise-sensitive circuits. The MAX1640's high-side current sensing allows the load to connect directly to ground, eliminating ground-potential errors. The MAX1641 incorporates a low-side current sense.

The MAX1640/MAX1641 step-down pulse-width-modulation (PWM) controllers use an external P-channel MOSFET switch and an optional, external N-channel MOSFET synchronous rectifier for increased efficiency. An internal low-dropout linear regulator provides power for the internal reference and circuitry as well as the gate drive for the N-channel synchronous rectifier.

The MAX1640/MAX1641 are available in space-saving, 16-pin narrow QSOP packages.

Simplified Block Diagram

MAX1640, MAX1641: Typical Operating Circuit MAX1640, MAX1641: 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 .