DESCRIPTION

KEY FEATURES

The LX1662/62A and LX1663/63A are

Monolithic Switching Regulator Con-

troller IC’s designed to provide a low cost,

high performance adjustable power supply

for advanced microprocessors and other

applications requiring a very fast transient

response and a high degree of accuracy.

Short-Circuit Current Limiting with-

out Expensive Current Sense Resistors.

Current-sensing mechanism can use PCB

trace resistance or the parasitic resistance of

the main inductor.

The LX1662A and

LX1663A have reduced current sense com-

parator threshold for optimum perfor-

mance using a PCB trace. For applications

requiring a high degree of accuracy, a

conventional sense resistor can be used to

sense current.

Programmable Synchronous Recti-

fier Driver for CPU Core.

The main

output is adjustable from 1.3V to 3.5V using

a 5-bit code. The IC can read a VID signal

set by a DIP switch on the motherboard, or

hardwired into the processor’s package (as

processors). The 5-bit code adjusts the

output voltage between 1.30 and 2.05V in

50mV increments and between 2.0 and 3.5V

in 100mV increments, conforming to the

I 5-bit Programmable Output For CPU Core

Supply

I No Sense Resistor Required For Short-

Circuit Current Limiting

I Designed To Drive Either Synchronous Or

Non-Synchronous Output Stages

I Lowest System Cost Possible For Price-

Sensitive Pentium And Pentium II Class

Applications

I Soft-Start Capability

I Modulated, Constant Off-Time Architecture

For Fast Transient Response And Simple

System Design

I Available Over-Voltage Protection (OVP)

Crowbar Driver And Power Good Flag

(LX1663 only)

I Small, Surface-Mount Packages

Intel Corporation specification. The device

can drive dual MOSFET’s resulting in typical

efficiencies of 85 - 90% even with loads in

excess of 10 amperes. For cost sensitive

applications, the bottom MOSFET can be

replaced with a Schottky diode (non-syn-

chronous operation).

Smallest Package Size. The LX1662 is

available in a narrow body 14-pin surface

mount IC package for space sensitive appli-

cations. The LX1663 provides the additional

functions of Over Voltage Protection (OVP)

and Power Good (PWRGD) output drives

for applications requiring output voltage

monitoring and protection functions.

Ultra-Fast Transient Response Re-

duces System Cost. The modulated off-

time architecture results in the fastest tran-

sient response for a given inductor, reduc-

ing output capacitor requirements, and re-

ducing the total regulator system cost.

Over-Voltage Protection and Power

Good Flag. The OVP output in the LX1663

& LX1663A can be used to drive an SCR

crowbar circuit to protect the load in the

event of a short-circuit of the main MOSFET.

The LX1663 & LX1663A also have a logic-

level Power Good Flag to signal when the

output voltage is out of specified limits.

PRODUCT H IGHLIGHT

OF

LX1662/62A, LX1663/63A

APPLICATIONS

I Socket 7 Microprocessor Supplies

(including Intel Pentium Processor, AMD-

Processors)

I Pentium II and Deschutes Processor & L2-

Cache Supplies

I Voltage Regulator Modules

I General Purpose DC:DC Converter

Applications

P ACKAGE ORDER INFORMATION

T

Plastic DIP

14-pin

0 to 70

LX1662CN

LX1663CN

LX1662CD

LX1663CD

LX1662ACN

LX1663ACN

LX1662ACD

LX1663ACD

N

Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (i.e. LX1662CDT)

Plastic DIP

16-pin

N

Plastic SOIC

14-pin

D

Plastic SOIC

16-pin

D

LX1662

IN A

Copyright © 1999

Rev. 1.1 11/99

1

IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.

SS

TDRV

V

CC

INV

V

CC_CORE

VID0

VID1

VID2

VID3

VID4

C

T

BDRV

GND

V

C1

U1

LX1662

VID3

C

5

1µF

12V

R

1

V

OUT

5V

14-pin, Narrow Body SOIC

Q

1

IRL3102

L

6.3V, 1500µF x 3**

14

13

12

11

10

9

1

2

3

4

5

6

7

8

C

8

680pF

VID2

VID1

VID0

VID4

C

3

0.1µF

2.5m

9

Supply Voltage

for CPU Core

6.3V

1500µF x3

** Three capacitors for Pentium

Four capacitors for Pentium II

Q

2

IRL3303

C

1

C

2

L

2

1µH