Note: All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a “controlled document”. Current revisions, if any, to these

specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation.

© 2001 Elantec Semiconductor, Inc.

General Description

The EL7551C is an integrated, synchronous step-down regulator with

output voltage adjustable from 1.0V to 3.8V. It is capable of delivering

1A continuous current at up to 95% efficiency. The EL7551C operates

at a constant frequency pulse width modulation (PWM) mode, making

external synchronization possible. Patented on-chip resistorless cur-

rent sensing enables current mode control, which provides cycle-by-

cycle current limiting, over-current protection, and excellent step load

response. The EL7551C is available in a fused-lead 16-pin QSOP

package. With proper external components, the whole converter fits

small size make this EL7551C ideal for desktop and portable

applications.

The EL7551C is specified for operation over the -40°C to +85°C tem-

perature range.

Typical Application Diagram

Manufactured under U.S. Patent No. 57,323,974

1

2

3

4

16

15

14

13

5

6

7

12

11

10

8

9

SGND

COSC

VDD

PGND

PGND

VIN

VIN

EN

PGND

VREF

FB

VDRV

LX

LX

VHI

PGND

R3

R2

L1

C3

C4

C1

C5

R1

C6

(3.3V,

1A)

(4.5V-

5.5V)

2.37k

10µH

1k

Ω

0.1µF

47µF

0.1µF

0.1µF 270pF

39

Ω

10µF

ceramic

EL7551C

Features

• Integrated synchronous MOSFETs

and current mode controller

• 1A continuous output current

• Up to 95% efficiency

• 4.5V to 5.5V input voltage

• Adjustable output from 1V to 3.8V

• Cycle-by-cycle current limit

• Precision reference

• ±0.5% load and line regulation

• Adjustable switching frequency to

1MHz

• Oscillator synchronization

possible

• Internal soft start

• Over temperature protection

• Under voltage lockout

• 16-pin QSOP package

Applications

• DSP, CPU Core and IO Supplies

• Logic/Bus Supplies

• Portable Equipment

• DC:DC Converter Modules

• GTL + Bus Power Supply

Ordering Information

Part No

Package

Tape & Reel

Outline #

EL7551CU

16-Pin QSOP

MDP0040

EL7551C - Preliminary

Monolithic 1 Amp DC:DC Step-down Regulator