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High-Speed Step-Down Controller with Synchronous Rectification for CPU Power

High-Accuracy, High-Efficiency CPU Power Supply Delivers >35A

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 4.5
VIN (V) (max) 5.5
VOUT1 (V) (min) 1.1
VOUT1 (V) (max) 4.5
IOUT1 (A) (max) 35
Switch Type External
Output Adjust. Method Resistor
Synchronous Switching? Yes
Power Good Signal Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 1000
300
600
Package/Pins SOIC (N)/16
Budgetary
Price (See Notes)
4.7
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 4.5
VIN (V) (max) 5.5
VOUT1 (V) (min) 1.1
VOUT1 (V) (max) 4.5
IOUT1 (A) (max) 35
Switch Type External
Output Adjust. Method Resistor
Synchronous Switching? Yes
Power Good Signal Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 1000
300
600
Package/Pins SOIC (N)/16
Budgetary
Price (See Notes)
4.7

Key Features

  • Better than ±1% Output Accuracy Over Line and Load
  • Greater than 90% Efficiency Using N-Channel MOSFETs
  • Pin-Selected High Switching Frequency: 300kHz, 600kHz, or 1MHz
  • Over 35A Output Current
  • Resistor-Divider Adjustable Output from 1.1V to 4.5V
  • Current-Mode Control for Fast Transient Response and Cycle-by-Cycle Current-Limit Protection
  • Short-Circuit Protection with Foldback Current Limiting
  • Crowbar Overvoltage Protection
  • Power-Good (PWROK) Output
  • Digital Soft-Start
  • High-Current (2A) Drive Outputs

Applications/Uses

  • Computers: Desktop, Workstation, Server
  • GTL Bus Termination
  • LAN Servers
  • Local DC-DC Converters for CPUs
  • Workstations

Description

The MAX1639 is an ultra-high-performance, step-down DC-DC controller for CPU power in high-end computer systems. Designed for demanding applications in which output voltage precision and good transient response are critical for proper operation, it delivers over 35A from 1.1V to 4.5V with ±1% total accuracy from a +5V ±10% supply. Excellent dynamic response corrects output transients caused by the latest dynamically clocked CPUs. This controller achieves over 90% efficiency by using synchronous rectification. Flying-capacitor bootstrap circuitry drives inexpensive, external N-channel MOSFETs.

The switching frequency is pin-selectable for 300kHz, 600kHz, or 1MHz. High switching frequencies allow the use of a small surface-mount inductor and decrease output filter capacitor requirements, reducing board area and system cost.

Output overvoltage protection is enforced by a crowbar circuit that turns on the low-side MOSFET with 100% duty factor when the output is 200mV above the normal regulation point. Other features include internal digital soft-start, a power-good output, and a 3.5V ±1% reference output. The MAX1639 is available in a 16-pin narrow SOIC package.

Simplified Block Diagram

MAX1639: Typical Operating Circuit MAX1639: Typical 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 .