MAX1638(2005) Просмотр технического описания (PDF) - Maxim Integrated

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MAX1638
(Rev.:2005)

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

Maxim Integrated 

19-1313; Rev 1; 8/05

EVAALVUAAILTAIOBNLEKIT

High-Speed Step-Down Controller with

Synchronous Rectification for CPU Power

General 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 synchro-

nous 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 out-

put 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 fea-

tures such as a digitally programmable output;

adjustable transient response; and selectable 0.5%, 1%,

or 2% AC load regulation. Fast recovery from load tran-

sients is ensured by a GlitchCatcher™ current-boost cir-

cuit 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% refer-

ence output.

________________________Applications

Pentium Pro™, Pentium II™, PowerPC™, Alpha™,

and K6™ Systems

Workstations

Desktop Computers

LAN Servers

GTL Bus Termination

Ordering Information

PART

MAX1638EAG

MAX1638EAG+

TEMP RANGE

-40°C to +85°C

-40°C to +85°C

PIN-PACKAGE

24 SSOP

24 QSOP

+Denotes lead-free package.

Pin Configuration appears at end of data sheet.

Pentium Pro and Pentium II are trademarks of Intel Corp.

PowerPC is a trademark of IBM Corp.

Alpha is a trademark of Digital Equipment Corp.

K6 is a trademark of Advanced Micro Devices.

GlitchCatcher is a trademark of Maxim Integrated Products.

____________________________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

Typical Operating Circuit

VCC

VDD

AGND BST

TO VDD MAX1638 DH

LX

PWROK

D0

D1

DL

D2

D3

PGND

D4

REF

CSH

LG

CSL

FREQ

CC1

FB

CC2

INPUT

+5V

OUTPUT

1.3V TO 4.5V

________________________________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

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