AMS AS1331 is a 300mA Buck-Boost Synchronous DC/DC Converter. It is most suitable for applications with space constraints and when a regulated voltage higher or lower than the supply voltage is required. It can generate both positive and negative output voltages from a positive input voltage. Typical applications include portable devices, battery powered systems, and industrial applications.
AMS AS1331 is a 300mA Buck-Boost Synchronous DC/DC Converter. It is most suitable for applications with space constraints and when a regulated voltage higher or lower than the supply voltage is required. It can generate both positive and negative output voltages from a positive input voltage. Typical applications include portable devices, battery powered systems, and industrial applications.
austriamicrosystems AG
is now
ams AG
The technical content of this austriamicrosystems application note is still valid.
Contact information:
Headquarters:
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
e-Mail: ams_sales@ams.com
Please visit our website at www.ams.com
AS1331 - Demo Board Manual
Buck-Boost Converter
www.austriamicrosystems.com Revision 1.01 1 - 5
Demo Board Manual
AS1331
300mA Buck-Boost Synchronous DC/DC
Converter
www.austriamicrosystems.com/DC-DC_Buck-Boost/AS1331
ams AG
Technical content still valid
AS1331 - Demo Board Manual
Buck-Boost Converter
www.austriamicrosystems.com Revision 1.01 2 - 5
General Description
Board Description
Connector Description
Label Name Description Info
A
VIN
Supply Voltage
B
GND
Ground
Supply voltage ranging from 1.8V to 5.5V
C
EN
Enable Connector
Logic “high”: normal operation
Logic “low”: shutdown; quiescent current <1µA
If an external signal is applied remove jumper
“N”.
D
VOUT
Output Voltage Output voltage ranging from 2.5V to 3.3V
Measurement Point Description
Label Name Description Info
E
VIN
Supply Voltage
F
SW1
G
SW2
External Inductor
H
VOUT
Output Voltage
I
EN
Enable Voltage
J
FB
Feedback Voltage
K
GND
Ground
L
LBO
Low Battery Output
M
LBI
Low Battery Input
Measurement Points
N
EN
Enable
ON: The AS1331 is on.
OFF; The AS1324 is off and the current
into Vin is <1µA (typ).
No Jumper: Connect a valid enable signal
via external connector “C”.
O
LBI
Low Battery Input
GND / EXT
EXT: Pin LBI is connected to the voltage
divider R4/R5. LBO depends on voltage
divider.
GND: Pin LBI is connected to GND. LBO is
referenced to VOUT via internal voltage
divider.
No Jumper: not allowed! LBI must have a
valid signal
Fi
g
ure 1: Board Description - Connecto
r
s Fi
g
ure 2: Board Description
–
Measurement Points
ams AG
Technical content still valid
AS1331 - Demo Board Manual
Buck-Boost Converter
www.austriamicrosystems.com Revision 1.01 3 - 5
P
LBI
Low Battery Input
VIN / OUT
VOUT: LBI voltage divider is referenced to
VOUT.
VIN: LBI voltage divider is referenced to
VIN.
No Jumper: LBI voltage divider has no
signal.
Q
LBO
Low Battery Output
VOUT: Signal on LBO is connected via R3
to VOUT.
VIN: Signal on LBO is connected via R3 to
VIN.
No Jumper: An external pull-up resistor is
required for a valid LBO signal.
Getting Started
The AS1331 Demoboard is designed to work with the AS1331 adjustable or fixed output voltage version. The
difference between these two versions is the configuration of the resistor divider R1/R2.
Before using the Demoboard please make sure which chip is on the board and check whether R1/R2
configuration matches the AS1331 version. The marking of the chip can be found printed on the IC soldered on
the board.
By default an AS1331-AD (adj.) is mounted on the Demoboard.
Bill of Materials
Operational sequence
This demo board comes with the AS1331.
1. Drive the IC on the demo board only with the recommended settings and values as described in the
datasheet. If not present get the datasheet for the AS1331 from www.austriamicrtosystem.com.
2. Connect a +1.8V to +5.5V power supply (Vin “A” and GND “B”).
3. Perform measurements at the measurement points.
If there are questions do not hesitate to contact us. See contact information at the end of this manual.
Ref. Function Value Description Manufacturer Mfg. Order Nr.
C1 Input Capacitor 10.0 µF
0805 / X5R / 6.3V /
T=0.95mm
Murata GRM219R60J106KE19
C2 Output Capacitor 22.0 µF
1206 / X5R / 16V /
T=1.8mm
Murata GRM31CR61C226KE15
L1 Coil 6.8µH
300mΩ / 0.89A /
3.0x3.0x1.5mm
Coilcraft LPS3015-682ML_
R1 390 kΩ 0805
R2
FB Voltage divider;
for adj. Vout = 3.3V
240 kΩ 0805
R1 0 Ω 0805
R2
FB Voltage divider;
for fixed Vout=3.3V
not used
R3 LBO pull-up resistor 100 kΩ 0805
R4 240 kΩ 0805
R5
LBI Voltage divider
100 kΩ 0805
ASRP
TDFN 10-pin
3.0x3.0x0.75mm
Austriamicrosystems AG AS1331-BTDT-AD
U1
DC/DC Buck-Boost
Converter
ASRU
TDFN 10-pin
3.0x3.0x0.75mm
Austriamicrosystems AG AS1331-BTDT-33
ams AG
Technical content still valid
AS1331 - Demo Board Manual
Buck-Boost Converter
www.austriamicrosystems.com Revision 1.01 4 - 5
Layout of Demo Board
Board schematics and layout
Figure 3: Schematics
Figure 4: Top + Bottom Layer
ams AG
Technical content still valid
AS1331 - Demo Board Manual
Buck-Boost Converter
www.austriamicrosystems.com Revision 1.01 5 - 5
Copyright
Copyright © 1997-2010, austriamicrosystems AG, Tobelbaderstraße 30, 8141 Unterpremstätten - Graz, Austria -
Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted,
merged, translated, stored, or used without the prior written consent of the copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions
appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by
description regarding the information set forth herein or regarding the freedom of the described devices from
patent infringement. Austriamicrosystems AG reserves the right to change specifications and prices at any time
and without notice. Therefore, prior to designing this product into a system, it is necessary to check with
austriamicrosystems AG for current information.
This product is intended for use in normal commercial applications. Applications requiring extended temperature
range, unusual environmental requirements, or high reliability applications, such as military, medical life-support
or life-sustaining equipment are specifically not recommended without additional processing by
austriamicrosystems AG for each application. For shipments of less than 100 parts the manufacturing flow might
show deviations from the standard production flow, such as test flow or test location.
The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However,
austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not
limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect,
special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing,
performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise
or flow out of austriamicrosystems AG rendering of technical or other services.
Contact Information
Headquarters
austriamicrosystems AG
Tobelbaderstraße 30
A-8141 Unterpremstätten - Graz, Austria
T. +43 (0) 3136 500 0
F. +43 (0) 3136 5692
For Sales Offices, Distributors and Representatives, please visit:
http://www.austriamicrosystems.com/contact
ams AG
Technical content still valid
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AMS AS1331 is a 300mA Buck-Boost Synchronous DC/DC Converter. It is most suitable for applications with space constraints and when a regulated voltage higher or lower than the supply voltage is required. It can generate both positive and negative output voltages from a positive input voltage. Typical applications include portable devices, battery powered systems, and industrial applications.
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