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MAX1644
2A、低电压、降压型稳压器,内置同步整流与开关

业内尺寸最小的2A DC-DC,带有同步整流器


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概述
完整的数据资料 (PDF, 172kB)
英文 Download this datasheet in PDF format下载

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.

关键特性   应用/使用
  • ±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

 
  • +3.3V PC卡及CardBus应用
  • +5V至+3.3V/+2.5V转换
  • CPU子卡电源
  • CPU I/O电源
  • 台式机总线端接板
  • 笔记本电脑和亚笔记本电脑

    Key Specifications:   Switch-Mode DC-DC Power Supplies
    Part Number Topology VIN (min) (V) VIN (max) (V) Number of DC-DC Outputs Preset VOUT (V) Digital/VID Programmed Output Min. Adjustable VOUT (V) Max. Adjustable VOUT (V) IOUT (A) Operating Current, ICC (max) (mA) Fixed Freq/PWM Operation Operating Freq. (kHz) Internal Power Switch(es) Synchronous Rectifier Package Smallest Available Package (max w/pins) (mm2) Price**
    MAX1644  Step-Down 3 5.5 1 2.5
    3.3
    No 1.1 5.5 2 0.36 Yes 350 Yes Yes SSOP/16 50 $4.08 @ 1k
    See All Switch-Mode DC-DC Power Supplies (413)
    Notes:
    **This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

    图表
    MAX1644:典型工作电路
    典型工作电路

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    参考文献: 19-1457; Rev. 3; 2005-10-10
    本页最后一次更新: 2007-07-23




             


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