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

Industry's Smallest, Fastest-Response Pentium® Pro / Pentium II 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) 1.3
VOUT1 (V) (max) 3.5
IOUT1 (A) (max) 35
Switch Type External
Output Adjust. Method Digital/VID
Resistor
Synchronous Switching? Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 300
600
1000
Package/Pins SSOP/24
Budgetary
Price (See Notes)
5.8
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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) 1.3
VOUT1 (V) (max) 3.5
IOUT1 (A) (max) 35
Switch Type External
Output Adjust. Method Digital/VID
Resistor
Synchronous Switching? Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 300
600
1000
Package/Pins SSOP/24
Budgetary
Price (See Notes)
5.8

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
  • Digitally Programmable Output from 1.3V to 3.5V
  • Current-Mode Control for Fast Transient Response and Cycle-by-Cycle Current-Limit Protection
  • Short-Circuit Protection with Foldback Current Limiting
  • Glitch-Catcher Circuit for Fast Load-Transient Response
  • Crowbar Overvoltage Protection
  • Power-Good (PWROK) Output
  • Digital Soft-Start
  • High-Current (2A) Drive Outputs
  • Complies with Intel VRM 8.2 Specification

Applications/Uses

  • Computers: Desktop, Workstation, Server
  • GTL Bus Termination
  • LAN Servers
  • Pentium®
  • Workstations

Description

The MAX1638 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 1.3V to 3.5V 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.

The MAX1638 is available in 24-pin SSOP and QSOP (future package) packages, and offers additional features such as a digitally programmable output; adjustable transient response; and selectable 0.5%, 1%, or 2% AC load regulation. Fast recovery from load transients is ensured by a GlitchCatcher™ current-boost circuit that eliminates delays caused by the buck inductor. 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.

Simplified Block Diagram

MAX1638: Typical Operating Circuit MAX1638: 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 .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.