LM2736

Thin SOT23 750mA Load Step-Down DC-DC Regulator

General Description

The LM2736 regulator is a monolithic, high frequency, PWM

step-down DC/DC converter in a 6-pin Thin SOT23 package.

It provides all the active functions to provide local DC/DC

conversion with fast transient response and accurate regu-

lation in the smallest possible PCB area.

With a minimum of external components and online design

The ability to drive 750mA loads with an internal 350m

Ω

NMOS switch using state-of-the-art 0.5µm BiCMOS technol-

ogy results in the best power density available. The world

class control circuitry allows for on-times as low as 13ns,

thus supporting exceptionally high frequency conversion

over the entire 3V to 18V input operating range down to the

minimum output voltage of 1.25V. Switching frequency is

internally set to 550kHz (LM2736Y) or 1.6MHz (LM2736X),

allowing the use of extremely small surface mount inductors

and chip capacitors. Even though the operating frequencies

are very high, efficiencies up to 90% are easy to achieve.

External shutdown is included, featuring an ultra-low

stand-by current of 30nA. The LM2736 utilizes current-mode

control

and

internal

compensation

to

provide

high-

performance regulation over a wide range of operating con-

ditions. Additional features include internal soft-start circuitry

to reduce inrush current, pulse-by-pulse current limit, ther-

mal shutdown, and output over-voltage protection.

Features

n

Thin SOT23-6 package

n

3.0V to 18V input voltage range

n

1.25V to 16V output voltage range

n

750mA output current

n

550kHz (LM2736Y) and 1.6MHz (LM2736X)

switching frequencies

n

350m

Ω NMOS switch

n

30nA shutdown current

n

1.25V, 2% internal voltage reference

n

Internal soft-start

n

Current-Mode, PWM operation

n

WEBENCH online design tool

Applications

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Local Point of Load Regulation

n

Core Power in HDDs

n

Set-Top Boxes

n

Battery Powered Devices

n

USB Powered Devices

n

DSL Modems

n

Notebook Computers

Typical Application Circuit

Efficiency vs Load Current "X"

V

20124201

20124251

October 2004

© 2004 National Semiconductor Corporation

DS201242

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