AS1331

300mA Buck-Boost Synchronous DC/DC Converters

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Revision 1.03

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Datasheet

1 General Description

This special device is a synchronous buck-boost DC/DC

converter which can handle input voltages above, below,

or equal to the output voltage.

Due to the internal structure of the AS1331 which is

working continuously through all operation modes this

device is ideal for dual or triple cell alkaline/NiCad/NiMH

as well as single cell Li-Ion battery applications.

Because of the implemented Power Save Mode, the

solution footprint and the component count is minimized

and also over a wide range of load currents a high

conversion efficiency is provided.

The device includes two N-channel MOSFET switches

and two P-channel switches. Also following features are

implemented: a quiescent current of typically 22µA

(ideal for battery power applications), a shutdown

current less than 1µA, current limiting, thermal shutdown

and output disconnect.

The AS1331 is available in a 10-pin 3x3mm TDFN

package with fixed and adjustable output voltage.

2 Key Features

!

Input Voltage Range: 1.8V to 5.5V

!

Output Voltages:

- Fixed: 2.5V, 3.0V, 3.3V

- Adjustable: 2.5V to 3.3V

!

Output Current: 300mA @ 3.3V

!

Up to 90% efficiency

!

Power Good

!

Output Disconnection in Shutdown

!

Automatic transition between Buck and Boost mode

!

Ultra Low Quiescent Current: 22µA, Shutdown Cur-

rent <1µA (Active Low)

!

Short-Circuit Protection

!

Low Battery detection

!

Over Temperature Protection

!

10-pin 3x3mm TDFN package

3 Applications

The AS1331 is an ideal solution for handheld

computers, handheld instruments, portable music

players and PDA’s. Two and three cell Alkaline, NiCd or

NiMH or single cell Li battery powered products.

Figure 1. AS1331 - Typical Application Diagram

1.8 to 5.5V

AS1331-AD

22µF

On

Off

10µF

PGND

3

SW2

2

2.5V to 3.3V

6

EN

10

FB

5

VIN

1

VOUT

SW1

4

L1

6.8µH

8

LBO

7

LBI

GND

9

Low Battery Detect