Datasheet
AS1344
4 2 V, D C - D C B o o s t C o n v e r t e r w it h a d j u s ta b l e S o fts ta r t
1 General Description
The AS1344 boost converter contains a 1.4A internal
switch in a tiny TDFN-10 3x3mm package. The device
operates from a 0.9V to 3.6V supply, and can boost volt-
ages up to 42V output.
The output voltage can easily be adjusted by an external
resistor divider.
The AS1344 uses a unique control scheme providing
the highest efficiency over a wide range of load condi-
tions. An internal 1.4A MOSFET reduces external com-
ponent count, and a fixed high switching frequency
(1MHz) allows for tiny surface-mount components.
The AS1344 also features power-OK circuitry which
monitors the output voltage.
The device also offers a Softstart function which limits
the current during startup. The current during startup
can be easily adjusted with the value of R
V
. For R
V
=
0Ω, there is no softstart.
Additionally the AS1344 features a low quiescent supply
current and a shutdown mode to save power. During
shutdown an output disconnect switch separates the
input from the output.
The AS1344 is ideal for LCD or OLED panels with low
current requirements and can also be used in a wide
range of other applications.
The device is available in a low-profile TDFN-10 3x3mm
package.
2 Key Features
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5.5V to 42V Adjustable Output Voltage
0.9V to 3.6V Supply Voltage Range
High Output Current:
- 30mA @ 12V V
OUT
, from 1.5V V
CC
Efficiency: Up to 85%
Switching Frequency: 1MHz
Output Disconnect Function
Softstart Function with adjustable Current Limit
Output Discharge Function
Power-OK Output
Quiescent Current: 22µA
Shutdown Current: 0.1µA
TDFN-10 3x3mm Package
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3 Applications
The device is ideal for OLED display power supply, LCD
bias generators, mobile/cordless phones, palmtop com-
puters, PDAs and organizers, handy terminals, driving
LEDs or any other portable, battery-powered device.
Figure 1. AS1344 - Typical Application Diagram
R
V
V
CC
= 0.9V
to 3.6V
C
IN
VCC
R
3
POK
On
Off
V
CC
GND
EN
FB
R
2
GND
LX
L
1
VIN
SWOUT
VOUT
D
1
V
OUT
= 5.5V to 42V
C
OUT
AS1344
R
1
PGND
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AS1344
Datasheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
EN 1
POK 2
GND 3
VCC 4
PGND 5
10 FB
9 VOUT
AS1344
8 VIN
7 SWOUT
6 LX
Pin Descriptions
Table 1. Pin Descriptions
Pin Number
1
Pin Name
EN
Description
Active-High Enable Input.
A logic low on this pin shuts down the device and
reduces the supply current to 0.1µA.
GND: device in shutdown.
V
CC
: normal operation.
Power-OK.
0: V
OUT
< 90% of V
OUTNOM
.
1: V
OUT
> 90% of V
OUTNOM
.
Ground
+0.9V to +3.6V Supply Voltage.
Bypass this pin to GND with a
≥10µF
capacitor.
Ground.
Should be the starpoint of C
IN
and C
OUT
.
Inductor.
The drain of the internal N-channel MOSFET.
Note:
This pin is high impedance in shutdown.
Shutdown Disconnect Switch Out.
Disconnects the input from the output during
shutdown.
Supply Connection.
Connect a resistor between pin VIN and pin VCC for limiting
the input current during startup.
+5.5 to +42V Output Voltage.
This pin also powers the AS1344 after startup.
Bypass this pin to GND with a
≥4.7µF
capacitor.
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 5.5V to 42V by:
V
OUT
= 1.25V[1 + (R
1
/R
2
)]
2
3
4
5
6
7
8
9
10
POK
GND
VCC
PGND
LX
SWOUT
VIN
VOUT
FB
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AS1344
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 2
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 Character-
istics on page 4
is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Table 2. Absolute Maximum Ratings
Parameter
VCC, VIN, EN, SWOUT, POK, FB to GND
VOUT, LX to GND
Thermal Resistance
Θ
JA
ESD
Latch-Up
Operating Temperature Range
Storage Temperature Range
Junction Temperature
-200
-40
-65
36.7
2
+100
+85
+150
125
Min
Max
5
45
Units
V
ºC/W
kV
mA
ºC
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).
on PCB
HBM MIL-Std. 883E 3015.7
methods
@25°C,
JEDEC 78
Comments
Package Body Temperature
+260
ºC
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AS1344
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
CC
= EN
=
3.6V, T
AMB
= -40 to +85ºC (unless otherwise specified). Typ values are at T
AMB
= +25ºC.
Table 3. Electrical Characteristics
Symbol
V
CC
Parameter
Maximum Supply Voltage
Minimum Supply Voltage
Minimum Start-Up Voltage
V
OUT
I
Q
I
SHDN
ΔV
LNR
ΔV
LDR
η
V
FB
I
FB
Output Voltage Range
Quiescent Current
Shutdown Current
V
CC
Line Regulation
Load Regulation
Efficiency
Feedback Voltage
Feedback Input Bias Current
V
FB
= 1.3V
V
OUT
= 6V, V
FB
=1.3V
EN = GND,
T
AMB
= +25ºC
V
OUT
= 15V, I
LOAD
= 1mA,
V
CC
= 1.8 to 3.6V
V
OUT
= 15V,
I
LOAD
= 0 to 20mA
L
1
= 6.8µH, V
OUT
= 12V, I
LOAD
= 50mA
1.225
V
OUT
= 12V, R
V
= 0Ω, no load
V
OUT
= 12V, I
LOAD
= 1mA, R
V
= 0Ω
5.5
22
0.02
0.05
0.01
85
1.25
1
1.275
100
0.9
0.95
Condition
Min
Typ
Max
3.6
1.1
1.2
42
30
1
Unit
V
V
V
V
µA
µA
%/V
%/mA
%
V
nA
DC-DC Switches
R
LX
R
P_ON
I
LX_LEAK
I
P_LEAK
Control Inputs
V
IH
EN Input Threshold
V
IL
V
EN
I
EN
POK Output
V
OL
POK Output Low Voltage
POK Output High Leakage
Current
POK Threshold
Oscillator
f
CLK
Oscillator Frequency
Maximum Duty Cycle
0.85
90
1
95
1.15
MHz
%
POK sinking 1mA
POK = 3.6V
Falling edge, referenced to V
OUT(NOM)
87
0.01
1
90
0.2
500
93
V
nA
%
EN Input Voltage
EN Input Current
V
EN
= 0 to 3.6V
0
1
1.1V
≤
V
CC
≤
3.6V
0.7 x
V
CC
0.3 x
V
CC
3.6
NMOS Switch On-
Resistance
PMOS Switch On-
Resistance
LX Leakage Current
Switch Leakage Current
I
LX
= 100mA
I
SWout
= -100mA
V
LX
= 42V
P-channel
0.9
0.3
15
10
1.5
Ω
1.0
nA
V
V
nA
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AS1344
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7 Typical Operating Characteristics
Parts used for measurments: 6.8µH (MOS6020-682) Inductor, 10µF (GRM21BR60J106KE19) C
IN
and 4.7µF
(GRM32ER71H475KA88) C
OUT,
(PMEG4010BEA) D
1
;
Figure 3. Efficiency vs. Output Current; V
OUT
= 6V
100
90
80
70
60
50
40
30
0.1
1
10
100
Vin = 2.0V
Vin = 2.5V
Vin = 3.0V
Vin = 3.3V
Figure 4. Efficiency vs. Output Current; V
OUT
= 12V
100
90
80
70
60
50
40
30
0.1
1
10
100
Vin = 2.0V
Vin = 2.5V
Vin = 3.0V
Vin = 3.3V
Efficiency (%)
Output Current (mA)
Figure 5. Efficiency vs. Output Current; V
OUT
= 18V
100
90
80
70
60
50
Vin = 2.5V
Efficiency (%)
Output Current (mA)
Figure 6. Efficiency vs. Output Current; V
OUT
= 24V
80
70
60
Efficiency (%)
Efficiency (%)
50
40
30
20
10
0
Vin = 2.5V
Vin = 3.0V
Vin = 3.3V
40
30
0.1
1
10
Vin = 3.0V
Vin = 3.3V
100
0.1
1
10
100
Output Current (mA)
Figure 7. Efficiency vs. Input Voltage; V
OUT
= 12V
100
90
80
70
60
50
Iout = 10mA
Output Current (mA)
Figure 8. Efficiency vs. Input Voltage; I
OUT
= 10mA
100
90
80
70
60
50
Vout = 5.5V
Iout = 50mA
Iout = 100mA
Efficiency (%)
Efficiency (%)
40
30
0.9 1.2 1.5 1.8 2.1
2.4 2.7
40
30
Vout = 10V
Vout = 12V
Vout = 15V
3
3.3 3.6
0.9 1.2 1.5 1.8 2.1
2.4 2.7
3
3.3 3.6
Input Voltage (V)
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Input Voltage (V)
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