AS1331
300mA Buck-Boost Synchronous DC/DC
Converter
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/NiCd/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.
Ordering Information
and
Content Guide
appear at end of
datasheet.
Key Benefits & Features
The benefits and features of AS1331, 300mA Buck-Boost
Synchronous DC/DC Converter are listed below:
Figure 1:
Added Value of Using AS1331
Benefits
•
Ideal for single Li-Ion battery powered
applications
Features
•
Input voltage range: 1.8V to 5.5V
•
Output voltage range: 2.5V to 3.3V
•
Output current: 300mA @ 3.3V
•
Automatic transition between buck and boost mode
•
Short-circuit protection
•
Overtemperature protection
•
Output disconnection in shutdown
•
10-pin 3x3mm TDFN package
•
Supports a variety of end applications
•
Built-in self-protection
•
Small system area
ams Datasheet
[v1-06] 2015-Dec-07
Page 1
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AS1331 −
General Description
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.
Block Diagram
The functional blocks of this device are shown below:
Figure 2:
Typical Application Diagram
L1
6.8µH
4
1.8V to 5.5V
C
1
10µF
R
4
5
VIN
7
R
5
On
Off
LBI
6
EN
3
SW1
2
SW2
8
LBO
R
3
V
OUT
2.5V to 3.3V
Low Battery Detect
AS1331-AD
1
VOUT
10
FB
R
2
R
1
C
2
22µF
PGND
9
GND
Page 2
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ams Datasheet
[v1-06] 2015-Dec-07
AS1331 −
Pin Assignment
Pin Assignment
Figure 3:
Pin Diagram (Top View)
VOUT 1
SW2 2
PGND
3
SW1 4
VIN 5
11
10 FB
9 GND
AS1331
8
LBO
7 LBI
6 EN
Figure 4:
Pin Description
Pin Name
VOUT
SW1
PGND
SW2
Pin Number
1
2
3
4
Description
Output of the Buck/Boost Converter.
Buck/Boost Switch Pin.
Connect the inductor from SW1 to SW2.
Power Ground.
Both GND pins must be connected.
Buck/Boost Switch Pin.
Connect the inductor from SW1 to SW2. An
optional Schottky diode can be connected between this pin and
VOUT to increase efficiency.
Input Supply Pin.
A minimum 2.2μF capacitor should be placed
between VIN and GND.
Enable Pin.
Logic controlled shutdown input.
1 = Normal operation
0 = Shutdown; quiescent current <1μA
VIN must be present and stable before EN operation is valid during
start-up.
Low Battery Comparator Input.
1.25V Threshold. May not be left
floating. If connected to GND LBO is working as Output Power okay.
VIN
5
EN
6
LBI
7
ams Datasheet
[v1-06] 2015-Dec-07
Page 3
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AS1331 −
Pin Assignment
Pin Name
LBO
GND
Pin Number
8
9
Description
Low Battery Comparator Output.
This open-drain output is low
when the voltage on LBI is less than 1.25V.
Ground.
Both GND pins must be connected.
Feedback Pin.
Feedback input for the adjustable version. Connect a
resistor divider tap to this pin. The output voltage can be adjusted
from 2.5V to 3.3V by: V
OUT
= 1.25V[1 + (R
1
/R
2
)].
(1)
Exposed Pad.
This pad is not connected internally. It can be used for
ground connection between GND and PGND.
FB
10
NC
11
Note(s):
1. For the fixed Output Voltage Version contact this pin to VOUT.
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ams Datasheet
[v1-06] 2015-Dec-07
AS1331 −
Absolute Maximum Ratings
Absolute Maximum Ratings
Stresses beyond those listed in Absolute maximum Ratings may
cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any
other conditions beyond those indicated in
Electrical
Characteristics
is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device
reliability.
Figure 5:
Absolute Maximum Ratings
Parameter
SW1, SW2, VIN, VOUT, EN
PGND to GND
SW1, SW2
Electrostatic Discharge ESD
Thermal Resistance
θ
JA
Junction Temperature
Operating Temperature Range
Storage Temperature Range
Min
-0.3
-0.3
-0.3
±4
+33
150
-40
-65
Max
+7
+0.3
+7
Units
V
V
V
kV
ºC/W
ºC
Notes
HBM MIL-Std. 883E 3015.7
methods
85
125
ºC
ºC
The reflow peak soldering
temperature (body temperature)
specified is in accordance with
IPC/JEDEC J-STD-020D
“Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid
State Surface Mount Devices”.
The lead finish for Pb-free leaded
packages is matte tin (100% Sn).
Package Body Temperature
260
ºC
Relative humidity (non-condensing)
Moisture sensitivity level
5
1
85
%
Unlimited floor life time
ams Datasheet
[v1-06] 2015-Dec-07
Page 5
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