Rainbow-electronics MAX1639 Manual de usuario descargar pdf

________________General 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 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.

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. The MAX1639 is available in a 16-pin

narrow SOIC package.

________________________Applications

Local DC-DC Converters for CPUs

Workstations

Desktop Computers

LAN Servers

GTL Bus Termination

____________________________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

MAX1639

High-Speed Step-Down Controller with

Synchronous Rectification for CPU Power

________________________________________________________________

Maxim Integrated Products

19-1337; Rev 0; 2/98

PART

MAX1639ESE -40°C to +85°C

TEMP. RANGE PIN-PACKAGE

16 Narrow SO

_______________Ordering Information

__________

Typical Operating Circuit

Pin Configuration appears at end of data sheet.

AGND

REF

FREQ

CC1

CC2

PWROK

BST

PGND

TO V

CSH

OUTPUT

1.1V TO 4.5V

INPUT

+5V

CSL

MAX1639

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 408-737-7600 ext. 3468.

EVALUATION KIT

AVAILABLE

1 2 3 4 5 6 ... 12 13

Indice de contenidos

Pagina 1 - __________

________________General DescriptionThe MAX1639 is an ultra-high-performance, step-downDC-DC controller for CPU power in high-end computersystems. Desi

Pagina 2 - ELECTRICAL CHARACTERISTICS

Overvoltage ProtectionWhen the output exceeds the set voltage, the synchro-nous rectifier output (DL) is driven high (and DH is dri-ven low). This ca

Pagina 3

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power____________________________________________________________________

Pagina 4

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power12 _________________________________________________________________

Pagina 5

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power____________________________________________________________________

Pagina 6

FREQ Input VoltageMAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power2 ________________________________________________

Pagina 7 - Synchronous-Rectifier Driver

ELECTRICAL CHARACTERISTICS (continued)(VDD= VCC = +5V, PGND = AGND = 0V, FREQ = REF, TA= 0°C to +85°C, unless otherwise noted.) MAX1639_______________

Pagina 8

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power4 __________________________________________________________________

Pagina 9 - High-Side Current Sensing

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power____________________________________________________________________

Pagina 10 - Specifying the Inductor

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power6 __________________________________________________________________

Pagina 11 - Resistor Value

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power____________________________________________________________________

Pagina 12 - Selecting the Rectifier Diode

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power8 __________________________________________________________________

Pagina 13 - Efficiency Considerations

MAX1639High-Speed Step-Down Controller withSynchronous Rectification for CPU Power____________________________________________________________________

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Rainbow-electronics MAX1639 Manual de usuario

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