AS1312
Ultra Low Quiescent Current,
Hysteretic DC-DC Step-Up Converter
General Description
The AS1312 is an ultra low I
Q
hysteretic step-up DC-DC
converter.
The AS1312 achieves an efficiency of up to 94% and is designed
to operate from a +0.7V to +5.0V supply, the output voltage is
fixed in 50mV steps from +2.5V to 5.0V.
In order to save power the AS1312 features a shutdown mode,
where it draws less than 100nA. In shutdown mode the battery
is not connected to the output.
If the input voltage exceeds the output voltage the device is in
a feedthrough mode and the input is directly connected to the
output voltage.
In light load operation, the device enters a sleep mode when
most of the internal operating blocks are turned off in order to
save power. This mode is active approximately 50μs after a
current pulse provided that the output is in regulation.
The AS1312 also offers an adjustable low battery detection. If
the battery voltage decreases below a threshold defined by two
external resistors on pin LBI, the LBO output is pulled to logic
low. LBO is working as Power-OK when LBI is connected to GND.
The AS1312 is available in a 8-pin (2x2) TDFN and a 0.4mm pitch
8-pin WL-CSP package.
Ordering Information
and
Content Guide
appear at end of
datasheet.
Key Benefits & Features
The benefits and features of AS1312, Ultra Low Quiescent
Current, Hysteretic DC-DC Step-Up Converter are listed below:
Figure 1:
Added Value of Using AS1312
Benefits
• Ideal for single Li-Ion battery powered
applications
• Extended battery life
• Less power consumption
Features
• Wide input voltage range (0.7V to 5.0V)
• Feedthrough mode when V
IN
> V
OUT
• High efficiency up to 94%
• Low quiescent current of typ. 1μA
• Low shutdown current of less than 100nA
• Fixed output voltage range (2.5V to 5.0V)
• Peak output current of 200mA
• Output disconnect in shutdown
• Supports a variety of end applications
ams Datasheet
[v1-19] 2016-Apr-14
Page 1
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AS1312 −
General Description
Benefits
• Over temperature protection and shutdown
• Early power-fail warning
• Cost effective, small package
Features
• Integrated temperature monitoring
• Low battery detection
• 8-pin WL-CSP with 0.4mm pitch
• 8-pin TDFN (2mm x 2mm)
Applications
The AS1312 is an ideal solution for:
• Handheld devices
• Battery powered products
Block Diagram
The functional blocks of this device are shown below:
Figure 2:
AS1312 Block Diagram
V
IN
0.7V to 5.0V
L1 6.8µF
AS1312
LX
Zero
Crossing
Detector
VOUT
V
OUT
2.5V to 5.0V
C
OUT
22µF
R3
100 k
+
ON
EN
VIN
Driver &
Control
Logic
Startup
Circuitry
-
+
Imax
Detection
VREF
GND
0.6V
92.5% VREF
+
-
-
100mV
LBO
LBI
OFF
C
IN
22µF
REF
C
REF
100nF
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ams Datasheet
[v1-19] 2016-Apr-14
AS1312 −
Pin Assignment
Pin Assignment
Figure 3:
Pinout (Top View)
LBI
1
8
VIN
Pin A1
indicator
GND
2
AS1312
TDFN 8-pin 2x2mm
Exposed pad: GND
7
EN
A1
LBI
A2
GND
A3
LX
A4
VOUT
LX
3
6
LBO
B1
VIN
B2
EN
B3
LBO
B4
REF
VOUT
4
9
5
REF
Figure 4:
Pin Description
Pin Number
Pin Name
WL-CSP
A1
A2
A3
A4
B4
B3
B2
Description
Low Battery Comparator Input.
0.6V Threshold. May not be left
floating. If connected to GND, LBO is working as Power Output OK.
Ground
External Inductor Connector.
Output Voltage.
Decouple VOUT with a ceramic capacitor as close
as possible to VOUT and
GND.
Reference Pin.
Connect a 100nF ceramic capacitor to this pin.
Low Battery Comparator Output.
Open-drain output.
Enable Pin.
Logic controlled shutdown input.
1 = Normal operation;
0 = Shutdown; shutdown current <100nA.
Battery Voltage Input.
Decouple VIN with a ceramic capacitor as
close as possible to VIN and GND.
Exposed Pad.
This pad is not connected internally. Can be left
floating or connect to
GND
to achieve an optimal thermal
performance.
TDFN
1
2
3
4
5
6
7
LBI
GND
LX
VOUT
REF
LBO
EN
B1
8
VIN
-
9
NC
ams Datasheet
[v1-19] 2016-Apr-14
Page 3
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AS1312 −
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
Symbol
Parameter
Min
Max
Unit
Comments
Electrical Parameters
VIN, VOUT, EN, LBI, LBO to
GND
LX, REF to GND
Input Current
(latch-up immunity)
-0.3
-0.3
-100
7
V
OUT
+ 0.3
100
V
V
mA
JEDEC 78
Electrostatic Discharge
ESD
HBM
Electrostatic Discharge HBM
±2
kV
MIL 883 E method 3015
Temperature Ranges and Storage Conditions
θ
JA
(1)
Thermal
Resistance
WL-CSP
TDFN
-40
97
ºC/W
60
85
125
150
-55
150
125
ºC
ºC
ºC
ºC
ºC
for 8-pin (2x2) TDFN
for 8-pin WL-CSP
IPC/JEDEC J-STD-020
(2)
260
ºC
IPC/JEDEC J-STD-020
(2)
The lead for Pb-free leaded
packages is matte tin (100%
Sn)
T
AMB
T
J
Operating Temperature
Junction
Temperature
WL-CSP
TDFN
T
STRG
Storage Temperature Range
-55
WL-CSP
T
BODY
Package Body
Temperature
TDFN
RH
NC
Relative Humidity
(non-condensing)
5
85
%
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ams Datasheet
[v1-19] 2016-Apr-14
AS1312 −
Electrical Characteristics
Symbol
Parameter
WL-CSP
Min
Max
Unit
Comments
Represents an unlimited floor
life time
MSL
Moisture
Sensitivity Level
TDFN
1
Represents an unlimited floor
life time
Note(s) and/or Footnote(s):
1. 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.
2. The reflow peak soldering temperature (body temperature) is specified according IPC/JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Nonhermetic Solid State Surface Mount Devices”
Electrical Characteristics
All limits are guaranteed. The parameters with Min and Max
values are guaranteed by production tests or SQC (Statistical
Quality Control) methods.
V
IN
= 1.5V, C1 = C2 = 22μF, C
REF
= 100nF, Typical values are at
T
AMB
= 25ºC. Unless otherwise specified.
All limits are guaranteed.
The parameters with min and max values are guaranteed with
production tests or SQC (Statistical Quality Control) methods.
Figure 6:
Electrical Characteristics
Symbol
Parameter
Conditions
Input
Min
Typ
Max
Unit
V
IN
Input Voltage Range
Minimum Startup Voltage
T
AMB
= 25°C
Regulation
0.7
0.9
5.0
V
V
V
OUT
Output Voltage Range
I
LOAD
= 0mA to 10mA,
T
AMB
= 25°C
Output Voltage Tolerance
I
LOAD
= 0mA to 10mA
I
LOAD
= 0mA to 30mA,
T
AMB
= -20°C to 60°C
V
OUT
Lockout Threshold
(1)
Rising Edge
Operating Current
Quiescent Current V
IN
V
OUT
= 1.02xV
OUTNOM
,
REF = 0.99xV
OUTNOM
,
T
AMB
= 25°C
V
OUT
= 5V, No load,
T
AMB
= 25°C
2.5
-2
-4
-2
2.45
5.0
2
4
2
V
%
%
%
V
100
nA
I
Q
Quiescent Current V
OUT
0.7
1
1.3
μA
ams Datasheet
[v1-19] 2016-Apr-14
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