AT1308
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Feature
•Operating Voltage:2.5V~6.0V
•High Operating Frequency: 1MHz
•Built-in N-MOS, R
ds(on)
≒
0.3Ω (TYP)
•High Output Voltage: Up to 28V
•Shutdown Current <1µA
•Built-in Cycle-by-Cycle Current-limited.
•Built-in Soft-Start Function.
•1.5% 1.23V Reference.
•Tiny SOT-25 Package
Description
The AT1308 step-up converter is designed for
small or medium size LCD panel of high bias
voltage with a constant current to provide PDAs,
and other hand-held devices. It features a fast 1.0
MHz current-mode PWM control with a built-in
0.3Ω N-MOS that allows for smaller capacitor and
inductor. Fault condition protection uses cycle-by-
cycle current limiting to sense maximum inductor
current and thermal protection. Also included
soft-start circuitry eliminates inrush current during
start-up. The AT1308 is available in 5-pin SOT-25
packages.
Application
• STN/OLED Bias
• Personal Digital Assistants (PDAs)
• DSC
Block Diagram
VIN
LX
EN
ON/OFF
Control
Logic
VBG
1.23V
Soft-Start
Thermal
Protection
VBG
N
+
Control Logic
FB
-
Current Limit
400mA
+
-
GND
Aimtron reserves the right without notice to change this circuitry and specifications.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
WWW:
http://www.aimtron.com.tw
Fax: 886-3-563-0879
Email:
service@aimtron.com.tw
1
Rev A ; 01/18/05
AT1308
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Pin Configuration
SOT-25
(TOP VIEW)
LX
GND
FB
1
2
3
4
EN
5
VIN
Ordering Information
Part number
AT1308X
AT1308X_GRE
Package
SOT-25
SOT-25,Green
Marking
Date Code
,Date Code with one bottom line
Pin Description
Pin N0. Symbol
1
LX
2
GND
3
4
5
FB
EN
VIN
I/O
I
P
I
I
P
Description
Step-up Regulator N-MOS Drain. Place output diode and inductor.
Ground
Step-Up Regulator Feedback Input. Connect a resistive divider from
output to FB to analog ground.
Enable Control Input. Pull EN low to force the controller into shutdown.
If unused , connect EN to Vin for normal operation.
Power supply.
Absolute Maximum Ratings
[note1]
Parameter
VIN voltage
LX voltage
EN , FB to GND
Switch Current (I
LX
)
Continuous power dissipation (SOT-25 Ta=+25
O
C)
Operating Junction Temperature Range
Lead Temperature (Soldering 5 sec)
Storage Temperature
Package Thermal Resistance (Θ
JA
)
ESD Susceptibility (HBM)
ESD Susceptibility (MM)
Rated Value
-0.3 to +6.5
-0.3 to +30
-0.3 to +6.5
0.8
0.25
-30 to 85
260
-65 to 125
250
2
200
Unit
V
V
V
A
W
℃
℃
℃
℃/W
KV
V
Note1:
Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
WWW:
http://www.aimtron.com.tw
Fax: 886-3-563-0879
Email:
service@aimtron.com.tw
2
Rev A ; 01/18/05
AT1308
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Recommended Operation Conditions
Parameter
Power supply voltage
Operating temperature
Symbol
V
IN
Top
Min.
2.5
-20
Values
Typ.
―
+25
Max.
6.0
+85
Unit
V
℃
Electrical Characteristics
(V
IN
=2.5V, Ta=+25℃, unless otherwise noted)
Parameter
Operating V
IN
Range
Under Voltage Thershold
Switch- Off Input Current
Shutdown Current
Feedback Reference
FB Input Bais Current
Output Voltage Line Regulation
Switching Frequency
Maximum Duty
Soft-Start charging time
Switching Current Limit
LX ON Resistance
LX Leakage Current
EN Input Current
EN Input Level
Thermal Shutdown
Symbol
Test Condition
V
IN
input Voltage
V
IN
UVLO
I
IN1
I
IN3
V
FB
I
FB
f
OSC
D
MAX
t
SS
ILX
R
LX
I
Leakage
I
EN
V
IH
V
IL
V
IN
falling, 100mV hysteresis
No Switching
EN=0V
V
FB
=1.23V
2.5V< V
IN
<6.0V
Min.
2.5
Typ. Max. Units
-
6.0
V
V
uA
uA
V
uA
%
MHz
%
ms
mA
Ω
uA
uA
V
V
℃
-
2.2
-
-
100 120
-
-
1
1.212 1.23 1.248
-
-
1
-
-
-
0.1
1
90
0.5
400
0.3
-
-
-
-
120
-
-
-
-
-
1
8
-
0.8
V
IN
=3.0V,duty cycle=80%
ILX =350mA
V
LX
=29V, EN=0V
EN=5V
0.1V hysteresis
-
-
-
-
2.0
-
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
WWW:
http://www.aimtron.com.tw
Fax: 886-3-563-0879
Email:
service@aimtron.com.tw
3
Rev A ; 01/18/05
AT1308
Preliminary Product Information
Micro-Power Step up DC-DC Converter
Application Circuit
10uH
VIN
2.5V to 4.2V
4u7F/
6V3
L1
1uF
MBR140WS
3.3V/
50mA
VIN
LX
10uH
L2
10pF
500K
R1
10uF/
6V3
AT1308
EN
FB
R2
297K
GND
※
L1, L2 : SR0302 (0.25Ohm/0.8A)
※
V
OUT
=V
REF
(1+R1/R2)
X
Fig1. 1-Cell Li-Ion to 3.3V SEPIC Converter
10uH
VIN
3.0V to 6.0V
4u7F/
6V3
L1
1uF
MBR140WS
5V/
40mA
VIN
LX
10uH
L2
10pF
10uF/
6V3
R1
500K
AT1308
EN
FB
R2
163K
GND
※
L1, L2 :SR0302 (0.25Ohm/0.8A)
※
V
OUT
=V
REF
(1+R1/R2)
X
Fig2. 4-Cell to 5V SEPIC Converter
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
WWW:
http://www.aimtron.com.tw
Fax: 886-3-563-0879
Email:
service@aimtron.com.tw
4
Rev A ; 01/18/05
AT1308
Preliminary Product Information
Micro-Power Step up DC-DC Converter
0.1uF
10uH
VIN
2.5V to 5.0V
4u7F/
6V3
L1
0.1uF
BAT54S
4.7uF/
16V
-15V/
4mA
15V/
4mA
BAT54S
VIN
LX
10pF
4.7uF/
16V
AT1308
EN
FB
500K
44K
GND
※
L1 :SR0302 (0.25Ohm/0.8A)
Fig3.
±15V
Dual Output Converter with Output Disconnect
10uH
VIN
2.5V to 5.0V
4.7uF/
6V3
L1
15V/
20mA
MBR140WS
VIN
LX
10uF/
16V
500K
R1
10pF
AT1308
EN
FB
44K
R2
GND
※
L1 :SR0302 (0.25Ohm/0.8A)
※
V
OUT
=V
REF
(1+R1/R2)
X
Fig4. 15V Boost Converter
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
WWW:
http://www.aimtron.com.tw
Fax: 886-3-563-0879
Email:
service@aimtron.com.tw
5
Rev A ; 01/18/05
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