AS1345
18V, High Efficiency, DC-DC Step-Up
Converter
General Description
The AS1345 high efficiency DC-DC step-up converter contains
an internal N-channel and an internal P-channel output
isolation switch.
The device operates from a 2.9V to 5.0V supply and can boost
voltages up to 18V.
A hysteretic control scheme is used to provide the highest
operating efficiency over a wide range of input and output load
conditions. The internal MOSFET switches reduce the external
component count and a high switching frequency allows the
use of tiny surface mount components.
The AS1345 employ a factory set current limit to reduce ripple
and external component size in low output current applications.
With a 500mA current limit the AS1345 is capable of providing
20mA @ 18V output.
Figure AS1345 – 1:
Available Products
Devices
AS1345A
AS1345B
AS1345C
AS1345D
Peak Coil Current
100mA
200mA
350mA
500mA
Output
adjustable or fixed
adjustable or fixed
adjustable or fixed
adjustable or fixed
For order related information, please refer to
“Ordering
Information” on page 24.
Built-in safety features protect the internal switches and output
components from fault conditions. Additional power-saving
attributes include a very low quiescent current and a true
shutdown mode.
Figure AS1345 – 2:
Key Benefits and Features
Benefits
Supports Lithium primary and re-chargeable
batteries
Supports a variety of end applications
Features
Input Voltage Range: 2.9V to 5.0V
Adjustable Output Voltage Range: 5.0V to 18V
18V, High Efficiency, DC-DC Step-Up Converter
AS1345 – 1
Benefits
Supports a variety of end applications
Allows optimization of circuit depending on output
power demands
Battery life improved
Battery supply isolated during shutdown
Fault tolerant
Features
Output Current up to 40mA
Inductor Peak Currents: 100, 200, 350 and 500 mA
90% Efficiency
True Shutdown
Short Circuit and Thermal Protection
Packages:
• 8-pin (2x2mm) TDFN
• 8-bumps (1.570mm x 0.895mm) WL-CSP with
0.4mm pitch
Small chipscale package
Applications
The AS1345 is ideal for small and low current demand LCD
panels, as well as for polymer LEDs (OLED), cell phones, PDAs,
readers, mobile terminals and 3D shutter glasses.
Figure AS1345 – 3:
Typical Application Diagram
10uF
10uH to 22uH
SWIN
VDD
10uF
100k
SWOUT
LX
Vout = 5.0V to 18V
VDD = 2.9V to 5.0V
POK
EN
AS1345
FB
GND
47pF
R2
1uF to 10uF
R3
ON
OFF
AS1345 – 2
18V, High Efficiency, DC-DC Step-Up Converter
Pin Assignments
Figure AS1345 – 4:
Pin Assignments (Top View)
Pin A1
indicator
VDD
1
8
GND
B1
GND
A1
VDD
AS1345
EN
2
7
LX
TDFN 8-pin 2x2mm
FB
3
B2
LX
A2
EN
Thermal pad: GND
6
SWOUT
B3
SWOUT
A3
FB
POK
4
9
5
SWIN
B4
SWIN
A4
POK
Figure AS1345 – 5:
Pin Descriptions
Pin Number
Pin Name
TDFN
WLP
Enable Pin.
Logic controlled shutdown input, 1.8V CMOS compatible;
1 = Normal operation
0 = Shutdown
On request a 100kΩ pull-down resistor can be enabled (factory set).
Ground
Inductor.
The drain of the internal N-channel MOSFET. Connect to
power inductor and to anode of a schottky diode.
Feedback Pin.
Feedback input to the gm error amplifier.
For an adjustable output voltage connect a resistor divider to this pin.
The output can be adjusted from 5.0V to 18V by: V
OUT
= V
REF
x (1 +
R2/R3)
If the fixed output voltage version is used, connect this pin to V
OUT
.
POK.
Open Drain Output. POK remains low while V
OUT
is less than 90%
of nominal V
OUT
. Connect a 100kΩ pull-up resistor from this pin to V
DD
.
Description
2
A2
EN
8
7
B1
B2
GND
LX
3
A3
FB
4
A4
POK
18V, High Efficiency, DC-DC Step-Up Converter
AS1345 – 3
Pin Number
Pin Name
TDFN
WLP
Shutdown Disconnect Switch Out.
Output pin of the internal
P-channel MOSFET. Connect to power inductor and decouple to GND
with a 10μF low ESR ceramic capacitor.
When the input disconnect feature is not desired, SWOUT should be
connected to SWIN and VDD.
Shutdown Disconnect Switch In.
Input pin of the internal P-channel
MOSFET.
Supply Voltage.
Connect to a 2.9V to 5.0V input supply. Bypass this pin
with a 10μF capacitor.
Exposed Pad.
This pad is not connected internally. This pin also
functions as a heat sink. Solder it to a large pad or to the circuit-board
ground plane to maximize power dissipation.
Description
6
B3
SWOUT
5
1
B4
A1
SWIN
VDD
9
-
NC
AS1345 – 4
18V, High Efficiency, DC-DC Step-Up Converter
Absolute Maximum Ratings
Stresses beyond those listed in the table below 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” on page 6
is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Figure AS1345 – 6:
Absolute Maximum Ratings
Parameter
Min
Max
Unit
Comments
Electrical Parameters
VDD, SWIN, SWOUT to GND
LX, FB to GND
Input Current (latch-up
immunity)
SWIN to SWOUT Current Limit
-0.3
-0.3
-100
7
20
100
1
V
V
mA
A
Norm: JEDEC 78
Electrostatic Discharge
Electrostatic Discharge HBM
±2
kV
Norm: MIL 883 E method 3015
Temperature Ranges and Storage Conditions
Junction temperature
-55
Storage temperature range
-55
WL-CSP
Package thermal
data
+150
60
ºC/W
TDFN
97
ºC
for TDFN
Junction-to-ambient thermal resistance is very
dependent on application and board-layout. In
situations where high maximum power
dissipation exists, special attention must be
paid to thermal dissipation during board
design.
Norm IPC/JEDEC J-STD-020
+260
TDFN
5
3
Moisture sensitive level
1
Represents a maximum floor life time of
unlimited for WL-CSP
85
%
Represents a maximum floor life time of 168h
for TDFN
ºC
Norm IPC/JEDEC J-STD-020
+110
+125
ºC
ºC
for WL-CSP
Package body
temperature
WL-CSP
Humidity non-condensing
Note: 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”.
18V, High Efficiency, DC-DC Step-Up Converter
AS1345 – 5
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