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MAX1845
Dual, High-Efficiency, Step-Down Controller with Accurate Current Limit


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Status
Active: In Production.

Data Sheet
FULL DATA SHEET (PDF, 616kB)
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Description
The MAX1845 is a dual PWM controller configured for step-down (buck) topologies that provides high efficiency, excellent transient response, and high DC output accuracy necessary for stepping down high-voltage batteries to generate low-voltage chipset and RAM power supplies in notebook computers. The CS_ inputs can be used with low-side sense resistors to provide accurate current limits or can be connected to LX_, using low-side MOSFETs as current-sense elements.

The on-demand PWM controllers are free running, constant on-time with input feed-forward. This configuration provides ultra-fast transient response, wide input-output differential range, low supply current, and tight load-regulation characteristics. The MAX1845 is simple and easy to compensate.

Single-stage buck conversion allows the MAX1845 to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, two-stage conversion (stepping down the 5V system supply instead of the battery at a higher switching frequency) allows the minimum possible physical size.

The MAX1845 is intended for generating chipset, DRAM, CPU I/O, or other low-voltage supplies down to 1V. For a single-output version, refer to the MAX1844 data sheet. The MAX1845 is available in 28-pin QSOP and 36-pin thin QFN packages.

An evaluation kit is available:  MAX1845EVKIT  

Key Features   Applications/Uses
  • Ultra-High Efficiency
  • Accurate Current-Limit Option
  • Quick-PWM™ with 100ns Load-Step Response
  • 1% VOUT Accuracy over Line and Load
  • Dual Mode™ Fixed 1.8V/1.5V/Adj or 2.5V/Adj Outputs
  • Adjustable 1V to 5.5V Output Range
  • 2V to 28V Battery Input Range
  • 200/300/420/540kHz Nominal Switching Frequency
  • Adjustable Overvoltage Protection
  • 1.7ms Digital Soft-Start
  • Drives Large Synchronous-Rectifier FETs
  • Power-Good Window Comparator
  • 2V ±1% Reference Output

 
  • 1.8V and 2.5V I/O Supplies
  • Chipset/RAM Supplies as Low as 1V
  • CPU Core Supplies
  • Notebook Computers

    Key Specifications:  Step-Down Switching Regulators
    Part Number VIN
    (V)
    VIN
    (V)
    VOUT
    (V)
    VOUT
    (V)
    Preset VOUT
    (V)
    Max. IOUT
    (A)
    Max. IOUT
    (A)
    Output Adjust. Method DC-DC Outputs Oper. Freq.
    (kHz)
    Package/Pins Smallest Available Pckg.
    (mm2)
    Price
    min max min max max w/pins See Notes
    MAX1845  2 28 1 5.5
    1.5
    1.8
    2.5
    10 10
    Preset
    Resistor
    2 540
    QSOP/28
    TQFN/36
    37.2 $3.85 @1k
    See All Step-Down Switching Regulators (264)

    Diagram
    MAX1845: Minimal Operating Circuit
    Minimal Operating Circuit

    Application Notes
  • Application Note 1845: Choosing the Right DC-DC Converter for Automotive Applications - MAX1845

    Evaluation Kits
  • MAX1845EVKIT

    Design Guides
  • Low-Power Notebook ICs (PDF)

    Reliability Reports
  • Reliability Report: AEC-MAX1845EEI_A.pdf MAX1845EEI.pdf
  • Show FIT data for:

    Software/Models
    none

    Ordering Information
    Notes:

    1. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
    2. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
    3. Part number suffixes: T or T&R = tape and reel;+ = RoHS/lead-free;# = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions.
    4. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.


    Devices: 1-8 of 8

    MAX1845 Free
    Sample
    Buy Status
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    Temp RoHS/Lead-Free?
    Materials Analysis
    MAX1845EEI    
    Active QSOP;28 pin;61.9 mm²
    Outline Drawing: 21-0055 (PDF)
    Land Pattern: 90-0173 (PDF)
    Use pkgcode/variation: E28-1*
    -40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX1845EEI-T    
    Active

    Land Pattern: Not Available

    -40°C to +85°C See data sheet
    MAX1845EEI+  
    Active QSOP;28 pin;61.9 mm²
    Outline Drawing: 21-0055 (PDF)
    Land Pattern: 90-0173 (PDF)
    Use pkgcode/variation: E28+1*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1845EEI+T    
    Active QSOP;28 pin;61.9 mm²
    Outline Drawing: 21-0055 (PDF)
    Land Pattern: 90-0173 (PDF)
    Use pkgcode/variation: E28+1*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1845ETX    
    Active TQFN;36 pin;37.2 mm²
    Outline Drawing: 21-0141 (PDF)
    Land Pattern: 90-0050 (PDF)
    Use pkgcode/variation: T3666-3*
    -40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX1845ETX-T    
    Active

    Land Pattern: Not Available

    -40°C to +85°C See data sheet
    MAX1845ETX+  
    Active TQFN;36 pin;37.2 mm²
    Outline Drawing: 21-0141 (PDF)
    Land Pattern: 90-0050 (PDF)
    Use pkgcode/variation: T3666+3*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1845ETX+T    
    Active TQFN;36 pin;37.2 mm²
    Outline Drawing: 21-0141 (PDF)
    Land Pattern: 90-0050 (PDF)
    Use pkgcode/variation: T3666+3*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis

    More Information
  • New Product Press Release 2001-02-13 

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    Document Ref.: 19-1955; Rev 2; 2003-03-20
    This page last modified: 2008-06-05


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