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MAX887, MAX887H
100%占空比、低噪声、降压型、PWM DC-DC转换器

内置功率MOSFET和检流电路,减少外部元件数并节省空间


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概述
完整的数据资料 (PDF, 160kB)
英文 Download this datasheet in PDF format下载

The MAX887 high-efficiency, step-down DC-DC converter provides an adjustable output from 1.25V to 10.5V. It accepts inputs from 3.5V to 11V and delivers 600mA. Operation to 100% duty cycle minimizes dropout voltage (300mV typ at 500mA). Synchronous rectification reduces output rectifier losses, resulting in efficiency as high as 95%.

Fixed-frequency pulse-width modulation (PWM) reduces noise in sensitive communications applications. Using a high-frequency internal oscillator allows tiny surface-mount components to reduce PC board area, and eliminates audio-frequency interference. A SYNC input allows synchronization to an external clock to avoid interference with sensitive RF and data-acquisition circuits.

The MAX887 features current-mode operation for superior load/line-transient response. Cycle-by-cycle current limiting protects the internal MOSFET and rectifier. A low-current (2.5µA typ) shutdown mode conserves battery life.

关键特性   应用/使用
  • 95% Efficiency
  • 600mA Output Current
  • Cycle-by-Cycle Current Limiting
  • Low-Dropout, 100% Duty-Cycle Operation, 300mV at 500mA
  • Internal 0.6Ω (typ) MOSFET
  • Internal Synchronous Rectifier
  • High-Frequency Current-Mode PWM
  • External SYNC or Internal 300kHz Oscillator
  • Guaranteed 260kHz to 340kHz Internal Oscillator Frequency Limits
  • 2.5µA Shutdown Mode

 
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    Key Specifications:   Switch-Mode DC-DC Power Supplies
    Part Number Topology VIN (min) (V) VIN (max) (V) Number of DC-DC Outputs 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**
    MAX887  Step-Down 3.5 11 1 No 1.25 10 0.6 0.5 Yes 440 Yes No SOIC/8 31 $2.44 @ 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
    MAX887,MAX887H:典型工作电路
    典型工作电路

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    参考文献: 19-1142; Rev. 0; 1996-09-01
    本页最后一次更新: 2007-05-31




             


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