MAX1644

PRODUCTION

2A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal Switches

Industry's Smallest 2A DC-DC with Synchronous Rectifier

Data Sheet (Rev. 3) Product Selection Table
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Overview

  • ±1% Output Accuracy
  • 95% Efficiency
  • Internal PMOS and NMOS Switches
    • 70mΩ On-Resistance at VIN = +4.5V
    • 100mΩ On-Resistance at VIN = +3V
  • Output Voltage
    • +3.3V or +2.5V Pin-Selectable
    • +1.1V to VIN Adjustable
  • +3V to +5.5V Input Voltage Range
  • 360µA (max) Operating Supply Current
  • < 1µA Shutdown Supply Current
  • Programmable Constant-Off-Time Operation
  • 350kHz (max) Switching Frequency
  • Idle Mode Operation at Light Loads
  • Thermal Shutdown
  • Adjustable Soft-Start Inrush Current Limiting
  • 100% Duty Cycle During Low-Dropout Operation
  • Output Short-Circuit Protection
  • 16-Pin SSOP Package

The MAX1644 constant-off-time, PWM step-down DC-DC converter is ideal for use in applications such as PC cards, CPU daughter cards, and desktop computer bus-termination boards. The device features internal synchronous rectification for high efficiency and reduced component count. It requires no external Schottky diode. The internal 0.10Ω PMOS power switch and 0.10Ω NMOS synchronous-rectifier switch easily deliver continuous load currents up to 2A. The MAX1644 produces a preset +3.3V or +2.5V output voltage or an adjustable output from +1.1V to VIN. It achieves efficiencies as high as 95%.

The MAX1644 uses a unique current-mode, constant-off-time, PWM control scheme, which includes an Idle Mode™ to maintain high efficiency during light-load operation. The programmable constant-off-time architecture sets switching frequencies up to 350kHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The device also features an adjustable soft-start to limit surge currents during start-up, a 100% duty cycle mode for low-dropout operation, and a low-power shutdown mode that disconnects the input from the output and reduces supply current below 1µA. The MAX1644 is available in a 16-pin SSOP package.

Applications

  • +3.3V PC Card and CardBus Applications
  • +5V to +3.3V/+2.5V Conversion
  • CPU Daughter Card Supply
  • CPU I/O Supplies
  • Desktop Bus-Termination Boards
  • Notebook and Subnotebook Computers
MAX1644
2A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal Switches
MAX1644: Typical Operating Circuit
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Documentation

Data Sheet 1

Reliability Data 1

Technical Articles 3

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Switching Regulators & Controllers 1
MAX1623
PRODUCTION 3A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal Switches
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Evaluation Kits

MAX1644EVKIT

Evaluation Kit for the MAX1644

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Features and Benefits

  • +3V to +5.5V Input Voltage Range
  • Output Voltage Preset to 1.5V
    • 2.5V or 3.3V Selectable
    • 1.1V to VIN Adjustable
  • 2A Output Current
  • 92% Efficiency
  • 300kHz Switching Frequency
  • Synchronous Rectification for Improved Efficiency
  • No External Schottky Diode Required
  • Less than 1µA typical IC Shutdown Current
  • Surface-Mount Construction
  • Fully Assembled and Tested

Product Details

The MAX1644 evaluation kit (EV kit) provides a 1.5V output voltage from a +3V to +5.5V input source. It delivers up to 2A output current with 92% (max) efficiency. The MAX1644 is a step-down switching regulator with an internal synchronous rectifier to reduce the number of external components. It features a resistor-programmable fixed off-time as well as current-mode operation for superior load- and line-transient response.

The MAX1644 EV kit can also be used to evaluate other output voltages by changing the feedback resistors (R1 and R2) or by using the preset +3.3V or +2.5V settings.

Applications

  • +3.3V PC Card and CardBus Applications
  • +5V to +3.3V/+2.5V Conversion
  • CPU Daughter Card Supply
  • CPU I/O Supplies
  • Desktop Bus-Termination Boards
  • Notebook and Subnotebook Computers
MAX1644EVKIT
Evaluation Kit for the MAX1644

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