MAX1845

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


Please check latest availability status for a specific part variant.

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.
MAX1845: Minimal Operating Circuit MAX1845: Minimal Operating Circuit Enlarge+

Key Features

  • 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

Applications/Uses

  • 1.8V and 2.5V I/O Supplies
  • Chipset/RAM Supplies as Low as 1V
  • CPU Core Supplies
  • Notebook Computers
Part NumberVIN
(V)
VIN
(V)
VOUT1
(V)
VOUT1
(V)
Preset VOUT
(V)
Output Adjust. MethodIOUT1
(A)
Switch TypeSynchronous SwitchingDC-DC OutputsOper. Freq.
(kHz)
Package/PinsBudgetary
Price
minmaxminmaxSee Notes
MAX1845 22815.5
1.5
1.8
2.5
Preset
Resistor
10ExternalYes2540
QSOP/28
TQFN/36
$1.65 @1k
See All Step-Down Switching Regulators (404)
Pricing 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 and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Technical Documents

App Note 1845 Choosing the Right DC-DC Converter for Automotive Applications

Quality and Environmental Data

Product Reliability Reports: MAX1845.pdf 
Lead-Free Package Tin (Sn) Whisker Reports
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

Quality Management System >
Environmental Management System >

 
Status:
Package:
Temperature:

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