AS1331
300mA Buck-Boost Synchronous DC/DC Converters
www.austriamicrosystems.com Revision 1.03 1 - 16
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-p in 3x3mm TDF N
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 musi c
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
C2
22µF
R2
R1
On
Off
C
1
10µF
PGND
3
SW2
2
V
OUT
2.5V to 3.3V
6
EN
10
FB
5
VIN
1
VOUT
SW1
4
L1
6.8µH
8
LBO
7
LBI
GND
9
R3
Low Battery Detect
