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

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 2
VIN (V) (max) 28
VOUT1 (V) (min) 1
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 10
Switch Type External
Preset VOUT (V) 1.5
1.8
2.5
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
# DC-DC Outputs 2
Switching Frequency (kHz) 540
Package/Pins TQFN/36
Budgetary
Price (See Notes)
1.75
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 2
VIN (V) (max) 28
VOUT1 (V) (min) 1
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 10
Switch Type External
Preset VOUT (V) 1.5
1.8
2.5
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
# DC-DC Outputs 2
Switching Frequency (kHz) 540
Package/Pins TQFN/36
Budgetary
Price (See Notes)
1.75

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

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.

Simplified Block Diagram

MAX1845: Minimal Operating Circuit MAX1845: Minimal Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .