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Maxim > Products > [Power and Battery Management] 
MAX1844
High-Speed Step-Down Controller with Accurate Current Limit for Notebook Computers


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Status
Active: In Production.

Data Sheet
FULL DATA SHEET (PDF, 872kB)
Download this datasheet in PDF formatDownload   Send this datasheet to any email addressE-Mail

Description
The MAX1844 pulse-width modulation (PWM) controller provides high efficiency, excellent transient response, and high DC output accuracy needed for stepping down high-voltage batteries to generate low-voltage CPU core or chipset/RAM supplies in notebook computers.

Maxim's proprietary Quick-PWM™ quick-response, constant-on-time PWM control scheme handles wide input/output voltage ratios with ease and provides 100ns “instant-on” response to load transients while maintaining a relatively constant switching frequency. Efficiency is enhanced by an ability to drive very large synchronous-rectifier MOSFETs. Accurate current sensing to ensure reliable overload protection is available using an external current-sense resistor in series with the synchronous rectifier. Alternatively, the synchronous rectifier itself can be used for less accurate current sensing at the lowest possible power dissipation.

Single-stage buck conversion allows the MAX1844 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 MAX1844 is intended for CPU core, chipset, DRAM, or other low-voltage supplies as low as 1V. It is available in 20-pin QSOP, and QFN packages and includes both adjustable overvoltage and undervoltage protection.

For a dual step-down PWM controller with accurate current limit, refer to the MAX1845. The MAX1714/ MAX1715 single/dual PWM controllers are similar to the MAX1844/MAX1845 but do not use current-sense resistors.

An evaluation kit is available:  MAX1844EVKIT  

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
  • 1.8V/2.5V Fixed or 1V to 5.5V Adjustable Output Range
  • 2V to 28V Battery Input Range
  • 200/300/450/600kHz Switching Frequency
  • Adjustable Overvoltage Protection
  • Adjustable Undervoltage Protection
  • 1.7ms Digital Soft-Start
  • Drives Large Synchronous-Rectifier FETs
  • 2V ±1% Reference Output
  • Power-Good Window Comparator

 
  		• 1.8V and 2.5V 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
    MAX1844  2 28 1 5.5
    1.8
    2.5
    		 4 4
    Preset
    Resistor
    		 1 300
    QFN/20
    QSOP/20
    TQFN/20
    		 26 $2.60 @1k
    See All Step-Down Switching Regulators (264)

    Diagram
    MAX1844: Functional Diagram
    Functional Diagram

    Application Notes
  		• Application Note 1845: Choosing the Right DC-DC Converter for Automotive Applications - MAX1844

    Evaluation Kits
  		• MAX1844EVKIT

    Reliability Reports
  		• Show FIT data for:
  		• Request Reliability Report 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: 1-10 of 10

    MAX1844 Free
    Sample    		 Buy Status
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    MAX1844EGP    
    		Active QFN;20 pin;26 mm²
    Outline Drawing: 21-0091 (PDF)
    Land Pattern: 90-0276 (PDF)
    Use pkgcode/variation: G2055-2*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX1844EGP-T    
    		Active

    Land Pattern: Not Available

    		-40°C to +85°C See data sheet
    MAX1844EEP    
    		Active QSOP;20 pin;54 mm²
    Outline Drawing: 21-0055 (PDF)
    Land Pattern: 90-0168 (PDF)
    Use pkgcode/variation: E20-1*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX1844EEP-T    
    		Active QSOP;20 pin;54 mm²
    Outline Drawing: 21-0055 (PDF)
    Land Pattern: 90-0168 (PDF)
    Use pkgcode/variation: E20-1*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX1844EEP+  
    		Active QSOP;20 pin;54 mm²
    Outline Drawing: 21-0055 (PDF)
    Land Pattern: 90-0168 (PDF)
    Use pkgcode/variation: E20+1*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1844EEP+T    
    		Active QSOP;20 pin;54 mm²
    Outline Drawing: 21-0055 (PDF)
    Land Pattern: 90-0168 (PDF)
    Use pkgcode/variation: E20+1*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1844ETP    
    		Active TQFN;20 pin;26 mm²
    Outline Drawing: 21-0140 (PDF)
    Land Pattern: 90-0009 (PDF)
    Use pkgcode/variation: T2055-4*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX1844ETP-T    
    		Active

    Land Pattern: Not Available

    		-40°C to +85°C See data sheet
    MAX1844ETP+  
    		Active TQFN;20 pin;26 mm²
    Outline Drawing: 21-0140 (PDF)
    Land Pattern: 90-0009 (PDF)
    Use pkgcode/variation: T2055+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1844ETP+T    
    		Active TQFN;20 pin;26 mm²
    Outline Drawing: 21-0140 (PDF)
    Land Pattern: 90-0009 (PDF)
    Use pkgcode/variation: T2055+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis

    More Information
  		• New Product Press Release 2001-06-13 

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    Document Ref.: 19-1993; Rev 3; 2002-11-20
    This page last modified: 2009-10-26


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