austriamicrosystems AG
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ams AG
The technical content of this austriamicrosystems datasheet is still valid.
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ams AG
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Data sheet
AS1337
2 0 0 m A , D C - D C St e p - U p C o n v e r t e r w i t h B u c k M o d e
1 General Description
The AS1337 is a synchronous, fixed frequency, highefficiency
DC-DC boost converter capable of supplying 3.3V @ 200mA
from two AA Cells. Compact size and minimum external parts
requirements make these devices perfect for modern portable
devices. The AS1337 offers automatic powersave mode to
increase efficiency at light loads. For input voltages higher
than VOUT the AS1337 will switch in a step down mode, so
that a Buck Boost function is realized.
The AS1337A offers a shutdown mode where the battery is
connected directly to the output enabling the supply of real-
time-clocks or memories.
2 Key Features
Input Voltage Range: 0.65V to 4.5V
Output Voltage Range: 2.5V to 5.0V
Delivers 200mA @ 3.3V (from two AA Cell)
up to 97% Efficiency
High-Speed Fixed-Frequency: 1.2MHz
Single-Cell Operation
In the shutdown mode of the AS1337B the battery is discon-
nected and the output is discharged.
Table 1. Standard Products
Model
AS1337A
AS1337B
Operation Mode
Battery Connected in Shutdown
Battery Disconnected in Shutdown and
Output Discharged
The AS1337 offers a POK (open-drain) feature which detects
output power fail of 10%.
The AS1337 is available in a
TDFN (3x3mm) 8-pin
package
.
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Figure 1. AS1337 - Typical Application Diagram – Dual Cell to 3.3V Synchronous Boost Converter
3.6V
Buck Mode
2x AA Cell Range
V
IN
Curve
Te
Boost Mode
1.6V
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Internal PMOS Synchronous Rectifier
Automatic Powersave Operation
Anti-Ringing Control Minimizes EMI
Logic Controlled Shutdown (< 1µA)
TDFN (3x3mm) 8-pin Package
3 Applications
The AS1337 is ideal for low-power applications where ultra-
small size is critical as in medical diagnostic equipment, hand-
held instruments, pagers, digital cameras, remote wireless
transmitters, MP3 players, LCD bias supplies, cordless
phones, GPS receivers, and PC cards.
L1
4.7µH
LX
VIN
On
Off
V
OUT
=3.3V
V
IN
= 2xAA
1.6V to 3.6V
C
IN
10µF
VOUT
FB
AS1337
EN
GND
POK
PGND
Revision 1.05
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V
OUT
= 3.3V
C
OUT
22µF
Low Start-Up Voltage: 0.85V
1 - 15
AS1337
Datasheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
VOUT 1
LX 2
8 FB
7 VIN
AS1337
PGND 3
GND 4
6 POK
5 EN
9 GND
Pin Descriptions
Table 2. Pin Descriptions
Pin Name
VOUT
Pin Number
1
LX
PGND
GND
EN
POK
VIN
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GND
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2
3
4
5
6
7
8
9
Revision 1.05
Description
Output Voltage.
Bias is derived from V
OUT
when V
OUT
exceeds V
IN
. PCB trace length from
V
OUT
to the output filter capacitor(s) should be as short and wide as is practical.
Switch Pin.
Connect an inductor between this pin and V
IN
. Keep the PCB trace lengths as short
and wide as is practical to reduce EMI and voltage overshoot. If the inductor current falls to zero,
or pin EN is low, an internal 100Ω anti-ringing switch is connected from this pin to V
IN
to minimize
EMI.
Note:
An optional Schottky diode can be connected between this pin and V
OUT
.
Power Ground.
Provide a short, direct PCB path between this pin and the output capacitor(s).
Ground
Enable Pin.
Logic controlled enable input.
1 = Normal operation
0 = Shutdown
Note:
In a typical application, EN should be connected to V
IN
through a 1MΩ
pull-up resistor.
POK.
High when V
OUT
is within regulation.
Input Voltage.
The AS1337 gets its start-up bias from V
IN
unless V
OUT
exceeds V
IN
, in which
case the bias is derived from V
OUT
. Thus, once started, operation is completely independent
from V
IN
. Operation is only limited by the output power level and the internal series resistance of
the supply.
Feedback Pin.
Feedback input to the g
m
error amplifier. Connect a resistor divider tap to this pin.
The output voltage can be adjusted from 2.5V to 5V by: V
OUT
= 1.23V[1 + (R
1
/R
2
)]
Exposed Pad Ground
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AS1337
Datasheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in
Table 3
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
Section 6 Electrical Characteristics on page 4
is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Table 3. Absolute Maximum Ratings
Parameter
Electrical Parameters
VIN to GND
FB to GND
All other pins to GND
Input Current (latch-up immunity)
Electrostatic Discharge
Human Body Model
-0.3
-0.3
-0.3
-100
5.5
5
6
100
V
V
V
mA
kV
ºC
Min
Max
Units
Notes
Temperature Ranges and Storage Conditions
Storage Temperature Range
Package Body Temperature
Humidity non-condensing
Moisture Sensitive Level
Te
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2
Norm: MIL 883 E method 3015
-55
+150
+260
ºC
5
85
%
1
Represents a max. floor life time of unlimited
Revision 1.05
Norm: JEDEC 78
The reflow peak soldering temperature (body
temperature) specified is in accordance with
IPC/
JEDEC J-STD-020 “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).
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AS1337
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
V
IN
= V
EN
= +1.2V, V
OUT
= +3.3V, Typ values @ T
AMB
= +25ºC (unless otherwise specified);
Table 4. Electrical Characteristics
Symbol
T
AMB
Input
Minimum Start-Up Voltage
Minimum Operating Voltage
V
IN
Regulation
V
FB
I
FB
Maximum Input Voltage
Output Voltage Adjust Range
Feedback Voltage
2.5
I
LOAD
= 1mA
EN = V
IN
1
Parameter
Operating Temperature Range
Conditions
Min
-45
Typ
Max
+85
Units
°C
V
V
0.85
0.65
Feedback Input Current
Operating Current
I
QPWS
I
SHDN
Switches
Quiescent Current
Shutdown Current
I
NMOSSWL
NMOS Switch Leakage
I
PMOSSWL
PMOS Switch Leakage
R
ONNMOS
NMOS Switch On Resistance
R
ONPMOS
PMOS Switch On Resistance
I
NMOS
f
SW
Shutdown
V
IH
V
IL
I
EN
NMOS Current Limit
Max Duty Cycle
Switching Frequency
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Enable Input Threshold
EN Input Current
Power-OK
POK Voltage Low
POK Leakage Current
Power-OK Threshold
Te
Thermal Protection
T
ENM
ΔT
ENM
Overtemperature Protection
Overtemperature Protection Hysteresis
1. Minimum V
IN
operation after start-up is only limited by the battery’s ability to provide the necessary power as it enters a deeply dis-
charged state.
2. I
QPWS
is measured at V
OUT
. Multiply this value by V
OUT
/V
IN
to get the equivalent input (battery) current.
Note:
All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality
Control) methods.
www.austriamicrosystems.com/DC-DC_Step-Up/AS1337
Revision 1.05
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1.192
1.23
1
1.268
V
V
FB
= 1.25V
nA
V
FB
= 1.4V
2
20
EN = GND, V
IN
= 3.3V
0.01
0.01
0.01
0.35
0.20
0.30
850
87
1.2
0.45
AS1337B only
V
OUT
= 3.3V
V
OUT
= 5V
V
OUT
= 3.3V
V
OUT
= 5V
V
FB
= 1V
80
0.95
1
EN = 5.0V
I
POK
=1mA
V
POK
= V
IN
or V
OUT
Falling Edge
86
0.01
0.1
1
88
145
10
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1.15
0.85
4.5
5
V
V
35
1
µA
µA
1
1
µA
µA
Ω
Ω
mA
%
1.5
MHz
0.3
1
0.4
100
91
V
µA
V
nA
%
ºC
ºC
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