LM3668

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SNVS449L – JUNE 2007 – REVISED MARCH 2011

LM3668 1A, High Efficiency Dual Mode Single Inductor Buck-Boost DC/DC Converter

Check for Samples: LM3668

1

FEATURES

APPLICATIONS

2

•

45µA Typical Quiescent Current

•

Handset Peripherals

•

For 2.8V/3.3V and 3.0/3.4V Versions:

•

MP3 Players

–

1A Maximum Load Current for

•

Pre-Regulation for Linear Regulators

•

PDAs

–

800mA Maximum Load Current for

•

Portable Hard Disk Drives

•

WiMax Modems

–

600mA Maximum Load Current for

DESCRIPTION

•

For 4.5/5V

The LM3668 is a synchronous buck-boost DC-DC

converter optimized for powering low voltage circuits

–

1A Maximum Load Current for

from a Li-Ion battery and input voltage rails between

2.5V and 5.5V. It has the capability to support up to

–

800mA Maximum Load Current for

1A output current over the output voltage range. The

LM3668 regulates the output voltage over the

–

700mA Maximum Load Current for

complete

input

voltage

range

by

automatically

switching between buck or boost modes depending

on the input voltage.

–

600mA Maximum Load Current for

The LM3668 has 2 N-channel MOSFETS and 2 P-

channel MOSFETS arranged in a topology that

•

2.2MHz PWM Fixed Switching Frequency (typ.)

provides continuous operation through the buck and

•

Automatic PFM-PWM Mode or Forced PWM

boost operating modes. There is a MODE pin that

Mode

allows the user to choose between an intelligent

•

Wide Input Voltage Range: 2.5V to 5.5V

automatic PFM-PWM mode operation and forced

PWM

operation.

During

PWM

mode,

a

fixed-

•

Internal Synchronous Rectification for High

frequency 2.2MHz (typ.) is used. PWM mode drives

Efficiency

load up to 1A. Hysteretic PFM mode extends the

•

Internal Soft Start: 600µs Maximum Startup

battery life through reduction of the quiescent current

to 45µA (typ.) at light loads during system standby.

Internal

synchronous

rectification

provides

high

•

0.01µA Typical Shutdown Current

efficiency. In shutdown mode (Enable pin pulled low)

•

Current Overload and Thermal Shutdown

the device turns off and reduces battery consumption

Protection

to 0.01µA (typ.).

•

Frequency Sync Pin: 1.6MHz to 2.7MHz

The LM3668 is available in a 12-pin WSON package.

A high switching frequency of 2.2MHz (typ.) allows

the use of tiny surface-mount components including a

2.2µH inductor, a 10µF input capacitor, and a 22µF

output capacitor.

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2

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PRODUCTION DATA information is current as of publication date.

Copyright © 2007–2011, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.