MAX1638

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

Industry's Smallest, Fastest-Response Pentium® Pro / Pentium II Supply, Delivers >35A


Please check latest availability status for a specific part variant.

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.
MAX1638: Typical Operating Circuit MAX1638: Typical Operating Circuit Enlarge+

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
Part Number VIN
(V)
VIN
(V)
VOUT1
(V)
VOUT1
(V)
Output Adjust. Method IOUT1
(A)
Switch Type Synchronous Switching DC-DC Outputs Oper. Freq.
(kHz)
Package/Pins Budgetary
Price
min max min max max See Notes
MAX1638  4.5 5.5 1.3 3.5
Digital/VID
Resistor
35 External Yes 1
300
600
1000
SSOP/24
$4.78 @1k
See All Step-Down Switching Regulators (345)
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.


MAX1638EVKIT: Evaluation Kit for the MAX1638

Technical Documents

App Note 280 Power Supplies for Telecom Systems

Quality and Environmental Data

Request Reliability Report for: MAX1638 
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.

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Type ID PDF Title
App Note 280 Power Supplies for Telecom Systems