LM2825

Integrated Power Supply 1A DC-DC Converter

General Description

The LM2825 is a complete 1A DC-DC Buck converter pack-

aged in a 24-lead molded Dual-In-Line integrated circuit

package.

Contained within the package are all the active and passive

components for a high efficiency step-down (buck) switching

regulator. Available in fixed output voltages of 3.3V, 5V and

12V, as well as two adjustable versions, these devices can

provide up to 1A of load current with fully guaranteed electri-

cal specifications.

Self-contained, this converter is also fully protected from out-

put fault conditions, such as excessive load current, short

circuits, or excessive temperatures.

Highlights

n

No external components required (fixed output voltage

versions)

n

Integrated circuit reliability

n

MTBF over 20 million hours

n

Radiated EMI meets Class B stipulated by CISPR 22

n

High power density, 35 W/in

3

n

24-pin DIP package profile (1.25 x 0.54 x 0.26 inches)

Features

n

Minimum design time required

n

3.3V, 5V and 12V fixed output versions

n

Two adjustable versions allow 1.23V to 15V outputs

n

Wide input voltage range, up to 40V

n

Low-power standby mode, I

n

High efficiency, typically 80%

4% output voltage tolerance

n

Excellent line and load regulation

n

TTL shutdown capability/programmable Soft-start

n

Thermal shutdown and current limit protection

n

−40˚C to +85˚C ambient temperature range

Applications

n

Simple high-efficiency step-down (buck) regulator

n

On-card switching regulators

n

Efficient pre-regulator for linear regulators

n

Distributed power systems

n

DC/DC module replacement

Standard Application

(Fixed output voltage versions)

Radiated EMI

Radiated emission of electromagnetic fields is measured at

10m distance. The emission levels are within the Class B

limits stipulated by CISPR 22.

30. . . .230 MHz

30 dB µV/m

230. . . .1000 MHz

37 dB µV/m

1. . . .10 GHz

46 dB µV/m

Connection Diagram

Ordering Information

Order Number LM2825N-3.3, LM2825N-5.0, LM2825N-12,

LM2825N-ADJ or LM2825HN-ADJ

See NS Package Number NA24F

DS012661-27

DS012661-1

DS012661-2

“NC (Do not use)” pins: See

Figure 11.

Top View

May 1997

© 1997 National Semiconductor Corporation

DS012661

www.national.com