FB

2.8V/3.3V

SW1

SW2

EN

LM3668

PVIN

PGND

SYNC/MODE

VSEL

L = 2.8V

H = 3.3V

VIN = 2.5V - 5.5V

SGND

VOUT

VDD

C2

22 2F

C1

10 2F

2.2 2H

NC

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LM3668

SNVS449O – JUNE 2007 – REVISED APRIL 2015

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

1 Features

2 Applications

1

•

45-µA Typical Quiescent Current

•

Handset Peripherals

•

For 2.8-V-3.3-V and 3-V-3.4-V Versions:

•

MP3 Players

•

Pre-Regulation for Linear Regulators

–

1-A Maximum Load Current for

•

PDAs

–

800-mA Maximum Load Current for

•

Portable Hard Disk Drives

•

WiMax Modems

–

600-mA Maximum Load Current for

3 Description

•

For 4.5 V-5 V

The LM3668 is a synchronous buck-boost DC-DC

converter optimized for powering low voltage circuits

–

1-A Maximum Load Current for

from a Li-Ion battery and input voltage rails between

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

–

800-mA Maximum Load Current for

1-A output current over the output voltage range. The

LM3668 regulates the output voltage over the

complete

input

voltage

range

by

automatically

–

700-mA Maximum Load Current for

switching between buck or boost modes depending

on the input voltage.

–

600-mA Maximum Load Current for

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

channel MOSFETS arranged in a topology that

•

2.2-MHz PWM Fixed Switching Frequency

provides continuous operation through the buck and

(Typical)

boost operating modes. There is a MODE pin that

•

Automatic PFM-PWM Mode or Forced PWM

allows the user to choose between an intelligent

Mode

automatic PFM-PWM mode operation and forced

PWM

operation.

During

PWM

mode,

a

fixed-

•

Wide Input Voltage Range: 2.5 V to 5.5 V

frequency 2.2 MHz (typical) is used. PWM mode

•

Internal Synchronous Rectification for High

drives load up to 1 A. Hysteretic PFM mode extends

Efficiency

the battery life through reduction of the quiescent

•

Internal Soft Start: 600-µs Maximum Start-Up

current to 45 µA (typical) at light loads during system

standby. Internal synchronous rectification provides

high efficiency. In shutdown mode (EN pin pulled

•

0.01-µA Typical Shutdown Current

low), the device turns off and reduces battery

•

Current Overload and Thermal Shutdown

consumption to 0.01 µA (typical).

Protection

A high switching frequency of 2.2 MHz (typical)

•

Frequency Sync Pin: 1.6 MHz to 2.7 MHz

allows the use of tiny surface-mount components

including a 2.2-µH inductor, a 10-µF input capacitor,

Typical Application Circuit

and a 22-µF output capacitor.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

LM3668

WSON (12)

3.00 mm x 3.00 mm

(1) For all available packages, see the orderable addendum at

the end of the datasheet.

1

An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.