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MAX1927, MAX1928
Low-Output-Voltage, 800mA, PWM Step-Down DC-DC Converters


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Description
FULL DATA SHEET (PDF, 308kB)
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The MAX1927/MAX1928 800mA step-down converters power low-voltage microprocessors in compact equipment requiring the highest possible efficiency. The MAX1927/MAX1928 are optimized for generating low output voltages (down to 750mV) at high efficiency using small external components. The supply voltage range is from 2.6V to 5.5V and the guaranteed minimum output current is 800mA. 1MHz pulse-width modulation (PWM) switching allows for small external components. A unique control scheme minimizes ripple at light loads, while maintaining a low 140µA quiescent current.

The MAX1927/MAX1928 include a low on-resistance internal MOSFET switch and synchronous rectifier to maximize efficiency and minimize external component count. No external diode is needed. 100% duty-cycle operation allows for a dropout voltage of only 340mV at 800mA. Other features include internal soft-start, power-OK (POK) output, and selectable forced PWM operation for lower noise at all load currents.

The MAX1928 is available with several preset output voltages: 1.5V (MAX1928-15), 1.8V (MAX1928-18), and 2.5V (MAX1928-25). The MAX1927R has adjustable output range down to 0.75V. The MAX1927/MAX1928 are available in a tiny 10-pin µMAX package.

Key Features   Applications/Uses
  • 800mA Output Current
  • Output Voltages from 0.75V to 5V
  • 2.6V to 5.5V Input Voltage Range
  • Power-OK Output
  • No Schottky Diode Required
  • Selectable Forced PWM Operation
  • 1MHz Fixed-Frequency PWM Operation
  • 140µA Quiescent Current
  • Soft-Start
  • 10-Pin µMAX Package

     
  • Battery-Powered Equipment
  • DSP Core Power
  • PDAs and Palmtops
  • WCDMA Handsets

    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**
    MAX1927  Step-Down 2.6 5.5 1  -  No 0.75 5 1 0.24 Yes 1000 Yes Yes uMAX/10 15 $1.60 @ 1k
    MAX1928  1.5
    1.8
    2.5
     -   -  $1.60 @ 1k
    See All Switch-Mode DC-DC Power Supplies (421)
    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.

    Diagram
    MAX1927, MAX1928: Typical Operating Circuit
    Typical Operating Circuit

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    Document Ref.: 19-2527; Rev 0; 2002-08-29
    This page last modified: 2007-07-16



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