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General Description
Figure 1:
Added Value of Using AS1310
Benefits
Ideal for single Li-Ion battery powered applications
Extended battery life
Supports a variety of end applications
ams Datasheet
[v1-11] 2015-Jan-28
AS1310
Ultra Low Quiescent Current,
Hysteretic DC-DC Step-Up Converter
The AS1310 is an ultra low quiescent current hysteretic step-up
DC-DC converter optimized for light loads (60mA), where it achieves efficiencies of up to 92%.
AS1310 operates from a 0.7V to 3.6V supply and supports output voltages between 1.8V and 3.3V. Besides the available
AS1310 standard variants any variant with output voltages in
50mV steps are available.
If the input voltage exceeds the output voltage the device is in a feed-through 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.
In order to save power the AS1310 features a shutdown mode, where it draws less than 100nA. During shutdown mode the battery is disconnected from the output.
The AS1310 also offers adjustable low battery detection. If the battery voltage decreases below the threshold defined by two external resistors on pin LBI, the LBO output is pulled to logic low.
The AS1310 is available in a TDFN (2x2) 8-pin package.
and
Content Guide appear at end of
datasheet.
Key Benefits & Features
The benefits and features of AS1310, Ultra Low Quiescent
Current, Hysteretic DC-DC Step-Up Converter are listed below:
Features
• Wide Input Voltage Range (0.7V to 3,6V)
• Feed through mode when V
IN
> V
OUT
• High Efficiency up to 92%
• Low Quiescent Current of typ. 1uA
• Low Shutdown Current of less than 100nA
• Fixed output voltage range (1.8V to 3.3V)
• Output Disconnect in shutdown
• Output current: 60mA @ VIN=0.9V, VOUT=1.8V
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Benefits
Over – temperature protection and shutdown
Early power-fail warning
Cost effective, small package
AS1310 −
General Description
Features
Integrated temperature monitoring
Adjustable low battery detection
• No external diode or transistor required
• 8-pin TDFN (2mm x 2mm)
Applications
The AS1310 is an ideal solution for single and dual cell powered devices as blood glucose meters, remote controls, hearing aids, wireless mouse or any light-load application.
Figure 2:
Typical Application Diagram
L1
6.8μH
V IN
0.7V to 3.6V
C
1
22μF
R 1
R 2
On
Off
8
VIN
1
LBI
7
EN
3
LX
AS1310
2
GND
6
LBO
4
VOUT
5
REF
R 3
Low Battery Detect
C 2
22μF
V
OUT
1.8V to 3.3V
C
REF
100nF
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ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Pin Assignment
Pin Assignment
Figure 3:
Pin Diagram (Top View)
LBI
1
GND
2
LX
3
VOUT
4
AS1310
Exposed pad
8
VIN
7
EN
6
LBO
5
REF
Figure 4:
Pin Description
Pin Number Pin Name
1
4
5
6
2
3
7
8
9
LBI
GND
LX
V
OUT
REF
LBO
EN
V
IN
NC
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 V
OUT
with a ceramic capacitor as close as possible to V
OUT
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 V
IN
with a 22μF ceramic capacitor as close as possible to V
IN
and GND.
Exposed Pad.
This pad is not connected internally. Can be left floating or connect to
GND
to achieve an optimal thermal performance.
ams Datasheet
[v1-11] 2015-Jan-28
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AS1310 −
Absolute Maximum R atings
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
Parameter Min Max Units Comments
Electrical Parameters
V
IN
, V
OUT
, EN, LBI, LBO to GND
-0.3
-55
+5 V
LX, REF to GND -0.3
V
OUT
+ 0.3
V
Input Current (latch-up immunity)
-100 100 mA Norm: JEDEC 78
Electrostatic Discharge HBM
Electrostatic Discharge
±2 kV Norm: MIL 883 E method 3015
Temperature Ranges and Storage Conditions
Thermal Resistance
θ
JA
58 ºC/W
Junction Temperature
Storage Temperature Range
+125
+125
ºC
ºC
Package Body Temperature +260 ºC
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).
Humidity non-condensing 5 85 %
Moisture Sensitive Level 1
Represents a maximum floor life time of unlimited
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ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Electrical Characteristics
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
T
AMB
Parameter
Operating Temperature
Range
V
IN
V
OUT
I
Q
I
SHDN
Conditions
Input
Input Voltage Range
Minimum Startup Voltage
I
LOAD
= 1mA, T
AMB
= +25°C
Regulation
Output Voltage Range
Output Voltage Tolerance
V
OUT
Quiescent Current V
Quiescent Current V
Shutdown Current
IN
OUT
I
LOAD
= 10 mA, T
AMB
= +25°C
I
LOAD
= 10mA
Rising Edge
Operating Current
V
OUT
= 1.02xV
OUTNOM
,
REF = 0.99xV
OUTNOM
,
T
AMB
= +25°C
V
OUT
= 1.02xV
ON
, REF =
0.99xV
ON
,
No load, T
AMB
= +25°C
T
AMB
= +25ºC
Min
-40
0.8
Typ
1
Max
+85
0.7
0.7
3.6
0.8
1.8
-2
-3
1.55
1.65
3.3
+2
+3
1.75
Units
°C
V
%
%
V
V
V
100 nA
1.2
μA
100 nA
ams Datasheet
[v1-11] 2015-Jan-28
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AS1310 −
Electrical Characteristics
Symbol
R
ON
I
PEAK
V
ENH
V
ENL
I
EN
I
REF
V
LBI
I
LBI
V
LBO
I
LBO
Parameter Conditions
Switches
NMOS
PMOS
NMOS maximum On-time
Peak Current Limit
Zero Crossing Current
V
OUT
= 3V
Enable, Reference
EN Input Voltage High
EN Input Voltage Low
EN Input Bias Current
REF Input Bias Current
EN = 3.6V, T
AMB
= +25°C
REF = 0.99xV
OUTNOM
,
T
AMB
= +25°C
Low Battery & Power-OK
Falling Edge LBI Threshold
LBI Hysteresis
LBI Leakage Current
LBO Voltage Low
LBO Leakage Current
Power-OK Threshold
Thermal Shutdown
I
LBI = 3.6V, T
LBO
= 1mA
AMB
LBI = 0V, Falling Edge
Thermal Protection
10°C Hysteresis
= +25°C
LBO = 3.6V, T
AMB
= +25°C
Min
3.6
320
5
0.35
0.5
4.2
400
20
4.8
480
35
0.7
Typ Max
0.1
100
100
Units
0.57
90
0.6
25
0.63
20
92.5
100
100
100
95 mV nA
%
V mV nA
V
V nA nA
Ω
Ω
μs mA mA
150 °C
Note(s) and/or Footnote(s):
1. The regulator is in startup mode until this voltage is reached. Caution: Do not apply full load current until the device output > 1.75V.
2. LBO goes low in startup mode as well as during normal operation if:
- The voltage at the LBI pin is below LBI threshold.
- The voltage at the LBI pin is below 0.1V and V
OUT
is below 92.5% of its nominal value.
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ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Typical Operating Characteristics
Typical Operating
Characteristics
T
AMB
= +25°C, unless otherwise specified.
Figure 7:
Efficiency vs. Output Current; V
OUT
= 1.8V
90
85
80
75
70
65
60
55
50
45
40
0.01
L1: XPL2010-682M
0.1
1 10
Output Current (mA)
100
Vin = 0.9V
Vin = 1.2V
Vin = 1.5V
1000
Figure 8:
Efficiency vs. Output Current; V
OUT
= 1.8V
90
85
80
L1: XPL7030-682M
75
70
65
60
55
50
45
40
0.01
0.1
1 10
Output Current (mA)
100
Vin = 0.9V
Vin = 1.2V
Vin = 1.5V
1000
ams Datasheet
[v1-11] 2015-Jan-28
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Page 8
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AS1310 −
Typical Operating Characteristics
Figure 9:
Efficiency vs. Output Current; V
OUT
= 3.0V
100
95
90
70
65
60
55
50
85
80
75
45
40
0.01
L1: XPL2010-682M
0.1
1 10
Output Current (mA)
100
Vin = 0.9V
Vin = 1.2V
Vin = 1.5V
Vin = 1.8V
Vin = 2.4V
1000
Figure 10:
Efficiency vs. Output Current; V
OUT
= 3.0V
100
95
90
85
80
75
70
65
60
L1: XPL7030-682M
55
50
45
40
0.01
0.1
1 10
Output Current (mA)
Vin = 0.9V
Vin = 1.2V
Vin = 1.5V
Vin = 1.8V
Vin = 2.4V
100 1000
ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Typical Operating Characteristics
Figure 11:
Efficiency vs. Input Voltage; V
OUT
= 1.8V
100
95
90
85
80
75
70
65
60
55
50
0.7
L1: XPL2010-682M
0.9
1.1
1.3
1.5
Input Voltage (V)
1.7
Iout = 1mA
Iout =10mA
Iout =50mA
1.9
Figure 12:
Maximum Output Current vs. Input Voltage
180
160
140
120
100
80
60
40
20
0
0 0.5
Vout = 1.8V
Vout = 3.0V
1 1.5
2
Input Voltage (V)
2.5
3
ams Datasheet
[v1-11] 2015-Jan-28
Page 9
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AS1310 −
Typical Operating Characteristics
Figure 13:
Start-up Voltage vs. Output Current
1
0.95
0.9
0.85
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0 1 2 3 4 5 6 7 8 9 10
Output Current (mA)
Figure 14:
RON vs. Temperature
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-40 -15 10 35
Temperature (°C)
60
PM OS
NM OS
85
ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Typical Operating Characteristics
Figure 15:
Output Voltage Ripple; V
IN
= 2V, V
OUT
= 3V,R load
= 100Ω
5μs/Div
ams Datasheet
[v1-11] 2015-Jan-28
Page 11
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Detailed Description
AS1310 −
Detailed Description
Hysteretic Boost Converter
Hysteretic boost converters are so called because comparators are the active elements used to determine ON-OFF timing via current and voltage measurements. There is no continuously operating fixed oscillator, providing an independent timing reference. As a result, a hysteretic or comparator based converter has a very low quiescent current. In addition, because there is no fixed timing reference, the operating frequency is determined by external component (inductor and capacitors) and also the loading on the output.
Ripple at the output is an essential operating component. A power cycle is initiated when the output regulated voltage drops below the nominal value of V
OUT
(0.99 x V
OUT
).
Inductor current is monitored by the control loop, ensuring that operation is always dis-continuous.
The application circuit shown in
requirements. However, further optimization may be useful, and the following is offered as a guide to changing the passive components to more closely match the end requirement.
Input Loop Timing
The input loop consists of the source DC supply, the input capacitor, the main inductor, and the N-channel power switch.
The ON timing of the N-channel switch is determined by a peak current measurement or a maximum ON time. In the AS1310, peak current is 400mA (typ) and maximum ON time is 4.2μs
(typ). Peak current measurement ensures that the ON time varies as the input voltage varies. This imparts line regulation to the converter.
The fixed ON-time measurement is something of a safety feature to ensure that the power switch is never permanently
ON. The fixed on-time is independent of input voltage changes.
As a result, no line regulation exists.
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ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Detailed Description
Figure 16:
Simplified Boost DCDC Architecture
0V
V
IN
C
IN
L1
SW1
SW2
Q
Q
I
PK
GND
FB
C
OUT
V
OUT
R
LOAD
0V
ON time of the power switch (Faraday’s Law) is given by:
(EQ1)
T
ON
=
LI
--------------------------------------------------------------------
V
IN
– I
PK
R
SW1
+ I
PK
R
L1
)
sec [volts, amps, ohms, Henry]
Applying Min and Max values and neglecting the resistive voltage drop across L1 and SW1;
(EQ2)
T
ON
_
MIN
=
L
MIN
I
PK
_
MIN
V
IN
_
MAX
(EQ3)
T
ON
_
MAX
=
L
MAX
I
PK
_
MAX
V
IN
_
MIN
ams Datasheet
[v1-11] 2015-Jan-28
Page 13
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AS1310 −
Detailed Description
Figure 17:
Simplified Voltage and Current Waveforms
0.99V
OUT_NOM
V
OUT
V
IND_TOFF
V
IND_TON
V
IN
0
V
B
C D A
B
C D
I
PK
0
I
L
T
OFF
T
WAIT
T
ON
SW1_on
SW2_off
T
T
OFF
T
SW2_on
SW1_off
T
WAIT
V
OUT
Ripple
T
T
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Another important relationship is the “volt-seconds” law.
Expressed as following:
(EQ4)
V
ON
T
ON
= V
OFF
T
OFF
Voltages are those measured across the inductor during each time segment.
Figure 17 shows this graphically with the shaded
segments marked “A & B”. Re-arranging
:
(EQ5)
T
-------------
T
OFF
=
V
OUT
– V
------------------------------
V
IN
The time segment called T
WAIT
in
is a measure of the
“hold-up” time of the output capacitor. While the output voltage is above the threshold (0.99xV
OUT
), the output is assumed to be in regulation and no further switching occurs.
ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Detailed Description
ams Datasheet
[v1-11] 2015-Jan-28
Inductor Choice Example
For the AS1310 V
IN_MIN
= 0.9V, V
OUT_MAX
= 3.3V,
gives
T
ON
=2.66T
OFF
.
Let the maximum operating on-time = 1μs.
Note that this is shorter than the minimum limit ON-time of
3.6μs. Therefore from
OFF
= 0.376μs. Using
, L
MAX
is obtained:
L
MAX
= 1.875μH. The nearest preferred value is 2.2μH.
This value provides the maximum energy storage for the chosen fixed ON-time limit at the minimum V
IN
.
Energy stored during the ON time is given by:
(EQ6)
E = 0.5L I
PK
)
2
Joules (Region A in
If the overall time period (T
ON
+ T
OFF
) is T, the power taken from the input is:
(EQ7)
P
IN
=
0.5L I
)
2
Watts
T
Assume output power is 0.8 P
IN
to establish an initial value of operating period T.
T
WAIT
is determined by the time taken for the output voltage to fall to 0.99xV
OUT
. The longer the wait time, the lower will be the supply current of the converter. Longer wait times require increased output capacitance. Choose T
WAIT
= 10% T as a minimum starting point for maximum energy transfer. For very low power load applications, choose T
WAIT
≥ 50% T.
(EQ8)
Output Loop Timing
The output loop consists of the main inductor, P-channel synchronous switch (or diode if fitted), output capacitor and load. When the input loop is interrupted, the voltage on the LX pin rises (Lenz’s Law). At the same time a comparator enables the synchronous switch, and energy stored in the inductor is transferred to the output capacitor and load. Inductor peak current supports the load and replenishes the charge lost from the output capacitor. The magnitude of the current from the inductor is monitored, and as it approaches zero, the synchronous switch is turned ON. No switching action continues until the output voltage falls below the output reference point (0.99 x V
OUT
).
Output power is composed of the DC component (Region C in
P
REGION_C
=
V
IN
I
--------
2
T
-------------
T
Output power is also composed of the inductor component
(Region B in
), neglecting efficiency loss:
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Page 16
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AS1310 −
Detailed Description
(EQ9)
P
REGION_B
=
0.5L I
PK
2
---------------------------
T
)
Total power delivered to the load is the sum of
(EQ10)
P
TOTAL
= V
IN
I
--------
2
T
-------------
T
+
0.5L I
PK
2
---------------------------
T
)
From
EQ 3 (using nominal values) peak current is given by:
(EQ11)
I
PK
=
T
L
V
---------------------
Substituting
into
(EQ12)
P
TOTAL
=
V
2
IN
T
----------------------- 0.9T
2TL
( )
0.9T incorporates a wait time T
WAIT
= 10% T
Output power in terms of regulated output voltage and load resistance is:
(EQ13)
P
OUT
=
V
2
R
LOAD
(EQ14)
Combining
2
OUT
R
LOAD
=
V
2
IN
T
----------------------- 0.9T
2TL
( )η
Symbol
η
reflects total energy loss between input and output and is approximately 0.8 for these calculations. Use
to plot duty cycle (T
ON
/T) changes for various output loadings and changes to V
IN
.
Input Capacitor Selection
The input capacitor supports the triangular current during the
ON-time of the power switch, and maintains a broadly constant input voltage during this time. The capacitance value is obtained from choosing a ripple voltage during the ON-time of the power switch. Additionally, ripple voltage is generated by the equivalent series resistance (ESR) of the capacitor. For worst case, use maximum peak current values from the datasheet.
(EQ15)
C
IN
=
I
--------------------------
V
T
ON
RIPPLE
(EQ16)
Using T
ON
= 1μs, and I
PEAK
= 480mA, and V
RIPPLE
= 50mV,
yields:
C
IN
= 9.6μF
Nearest preferred would be 10μF.
V
PK
_
RIPPLE
_
ESR
=
I
PK
R
ESR
ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Detailed Description
Typically, the ripple due to ESR is not dominant. ESR for the recommended capacitors (Murata GMR), ESR = 5m
Ω
to 10m
Ω
.
For the AS1310, maximum peak current is 480mA. Ripple due to ESR is 2.4mV to 4.8mV.
Ripple at the input propagates through the common supply connections, and if too high in value can cause problems elsewhere in the system. The input capacitance is an important component to get right.
(EQ17)
Output Capacitor Selection
The output capacitor supports the triangular current during the
OFF-time of the power switch (inductor discharge period), and also the load current during the wait time (Region D in
Figure 17 ) and ON-time (Region A in Figure 17 ) of the power
switch.
C
OUT
=
I
LOAD
( 1
−
0 .
(
T
ON
+
T
99 )
V
OUT
WAIT
_
NOM
)
Note(s):
There is also a ripple component due to the equivalent series resistance (ESR) of the capacitor.
Summary
User Application Defines:
V
INmin
, V
INmax
, V
OUTmin
, V
OUTmax
, I
LOADmin
, I
LOADmax
Inductor Selection:
Select Max on-time = 0.5μs to 3μs for AS1310. Use
calculate inductor value.
Use
to determine OFF-time.
Use
to check that power delivery matches load requirements assume 70% conversion efficiency.
to find overall timing period value of T at min V
IN
and max V
OUT
for maximum load conditions.
Input Capacitor Selection:
Choose a ripple value and use EQ 14
to find the value.
Output Capacitor Selection:
Determine T
WAIT
via
or
, and use
value.
ams Datasheet
[v1-11] 2015-Jan-28
Page 17
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Application Information
Figure 18:
AS1310 Block Diagram
AS1310 −
Application Information
The AS1310 is available with fixed output voltages from 1.8V to
3.3V in 50mV steps.
V
IN
0.7V to 3.6V
LX
L1 6.8µF
LBI
ON
OFF
EN
VIN
C
IN
22µF
GND
Zero
Crossing
Detector
AS1310
Driver &
Control
Logic
Imax
Detection
-
+
VREF
Startup
Circuit ry
0.6V
92.5% VREF
+
-
+
100mV
VOUT
C
OUT
22µF
V
OUT
1.8V to 3.3V
R3
LBO
REF
C
REF
100nF
Page 18
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AS1310 Features
Shutdown
. The part is in shutdown mode while the voltage at pin EN is below 0.1V and is active when the voltage is higher than 0.7V.
Note(s):
EN can be driven above V
IN
or V
OUT
, as long as it is limited to less than 3.6V.
Output Disconnect and Inrush Limiting
. During shutdown
V
OUT
is going to 0V and no current from the input source is running through the device. This is true as long as the input voltage is higher than the output voltage.
Feedthrough Mode.
If the input voltage is higher than the output voltage the supply voltage is connected to the load through the device. To guarantee a proper function of the
AS1310 it is not allowed that the supply exceeds the maximum allowed input voltage (3.6V).
In this feedthrough mode the quiescent current is 35μA (typ.).
The device goes back into step-up mode when the oputput voltage is 4% (typ.) below V
OUTNOM
.
ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Application Information
Power-OK and Low-Battery-Detect Functionality
LBO goes low in startup mode as well as during normal operation if:
• The voltage at the LBI pin is below LBI threshold (0.6V).
This can be used to monitor the battery voltage.
• LBI pin is connected to GND and V
OUT
is below 92.5% of its nominal value. LBO works as a power-OK signal in this case.
The LBI pin can be connected to a resistive-divider to monitor a particular definable voltage and compare it with a 0.6V internal reference. If LBI is connected to GND an internal resistive-divider is activated and connected to the output.
Therefore, the Power-OK functionality can be realized with no additional external components.
The Power-OK feature is not active during shutdown and provides a power-ON-reset function that can operate down to
V
IN
= 0.7V. A capacitor to GND may be added to generate a power-ON-reset delay. To obtain a logic-level output, connect a pull-up resistor R
3
from pin LBO to pin V
OUT
. Larger values for this resistor will help to minimize current consumption; a 100k
Ω resistor is perfect for most applications
.
For the circuit shown in the left of
, the input bias current into LBI is very low, permitting large-value resistor-divider networks while maintaining accuracy. Place the resistor-divider network as close to the device as possible. Use a defined resistor for R
2
and then calculate R
1
as:
(EQ18)
R
1
= R
2
⋅
V
------------
V
LBI
–
1
Where: V
LBI
is 0.6V ±30mV
ams Datasheet
[v1-11] 2015-Jan-28
Page 19
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AS1310 −
Application Information
Figure 19:
Typical Application with Adjustable Battery Monitoring
C
V
IN
0.7V to 3.6V
IN
22µF
ON
OFF
L1
6.8µH
LX
VIN
LBI
EN
AS1310
LBO
OUT
REF
GND
C
REF
100nF
Low Battery
Detect
V
OUT
1.8V to 3.3V
C
OUT
22µF
0V
Figure 20:
Typical Application with LBO working as Power-OK
C
V
IN
0.7V to 3.6V
IN
22µF
ON
OFF
L1
6.8µH
LX
VIN
LBO
AS1310
OUT
LBI
EN
REF
GND
C
REF
100nF
Power OK
Output
V
OUT
1.8V to 3.3V
C
OUT
22µF
0V
Page 20
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ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Application Information
ams Datasheet
[v1-11] 2015-Jan-28
Thermal Shutdown
To prevent the AS1310 from short-term misuse and overload conditions the chip includes a thermal overload protection. To block the normal operation mode all switches will be turned
OFF. The device is in thermal shutdown when the junction temperature exceeds 150°C. To resume the normal operation the temperature has to drop below 140°C.
A good thermal path has to be provided to dissipate the heat generated within the package. Otherwise it’s not possible to operate the AS1310 at its usable maximal power. To dissipate as much heat as possible from the package into a copper plane with as much area as possible, it’s recommended to use multiple vias in the printed circuit board. It’s also recommended to solder the Exposed Pad (pin 9) to the GND plane.
Note(s):
Continuing operation in thermal overload conditions may damage the device and is considered bad practice.
Always ON Operation
In battery powered applications with long standby times as blood glucose meters, remote controls, soap dispensers, etc., a careful battery management is required. Normally a complex power management control makes sure that the DCDC is only switched ON, when it is really needed. With AS1310 this complex control can be saved completely, since the AS1310 is perfectly suited to support always-ON operations of the application. The efficiency at standby currents of e.g. 2μAs is around 45%
.
Figure 21:
Efficiency vs. Output Current for Always ON Operation;
V
OUT
=3.3V
100
90
80
L1: XPL2010-682M
70
60
50
40
30
20
10
0
0.001
0.01
0.1
1
Output Current (mA)
Vin = 1.1V
Vin = 1.5V
10 100
Page 21
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AS1310 −
Application Information
Component Selection
Only four components are required to complete the design of the step-up converter. The low peak currents of the AS1310 allow the use of low value, low profile inductors and tiny external ceramic capacitors.
Inductor Selection
For best efficiency, choose an inductor with high frequency core material, such as ferrite, to reduce core losses. The inductor should have low DCR (DC resistance) to reduce the I²R losses, and must be able to handle the peak inductor current without saturating. A 6.8μH inductor with a >500mA current rating and
<500m
Ω
DCR is recommended.
Figure 22:
Recommended Inductors
Part Number
XPL2010-682M
EPL2014-682M
LPS3015-682M
LPS3314-682M
LPS4018-682M
XPL7030-682M
LQH32CN6R8M53L
LQH3NPN6R8NJ0L
LQH44PN6R8MJ0L
L
6.8μH
6.8μH
6.8μH
6.8μH
6.8μH
6.8μH
6.8μH
6.8μH
6.8μH
DCR
421m
Ω
287m
Ω
300m
Ω
240m
Ω
150m
Ω
59m
Ω
250m
Ω
210m
Ω
143m
Ω
Current
Rating
0.62A
0.59A
0.86A
0.9A
1.3A
9.4A
0.54A
0.7A
0.72A
Dimensions
(L/W/T)
2.0x1.9x1.0 mm
2.0x2.0x1.4 mm
3.0x3.0x1.5 mm
3.3x3.3x1.3 mm
3.9x3.9x1.7 mm
7.0x7.0x3.0 mm
3.2x2.5x1.55 mm
3.0x3.0x1.1 mm
4.0x4.0x1.1 mm
Manufacturer
Coilcraft www.coilcraft.com
Murata www.murata.com
Page 22
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ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Application Information
Capacitor Selection
The convertor requires three capacitors. Ceramic X5R or X7R types will minimize ESL and ESR while maintaining capacitance at rated voltage over temperature. The V
IN
capacitor should be
22μF. The V
OUT
capacitor should be between 22μF and 47μF. A larger output capacitor should be used if lower peak to peak output voltage ripple is desired. A larger output capacitor will also improve load regulation on V
OUT
for a list of capacitors for input and output capacitor selection.
Figure 23:
Recommended Input and Output Capacitors
Part Number
GRM21BR60J226ME99
GRM31CR61C226KE15
GRM31CR60J475KA01
C
22μF
22μF
47μF
TC
Code
X5R
X5R
X5R
Rated
Voltage
6.3V
16V
6.3V
Dimensions
(L/W/T)
0805, T=1.25mm
1206, T=1.6mm
1206, T=1.6mm
Manufacturer
Murata www.murata.com
On the pin REF a 10nF capacitor with an Insulation resistance
>1G
Ω
is recommended.
Figure 24:
Recommended Capacitors for REF
Part Number C
GRM188R71C104KA01 100nF
GRM31CR61C226KE15 100nF
TC
Code
Insulation
Resistance
Rated
Voltage
Dimensions
(L/W/T)
Manufacturer
X7R
X7R
>5G
Ω
>5G
Ω
16V
50V
0603,
T=0.8mm
0805,
T=1.25mm
Murata www.murata.com
Layout Considerations
Relatively high peak currents of 480mA (max) circulate during normal operation of the AS1310. Long printed circuit tracks can generate additional ripple and noise that mask correct operation and prove difficult to “de-bug” during production testing. Referring to
Figure 2 , the input loop formed by C1, V
IN and GND pins should be minimized. Similarly, the output loop formed by C2, V
OUT
and GND should also be minimized. Ideally both loops should connect to GND in a “star” fashion. Finally, it is important to return C
REF
to the GND pin directly.
ams Datasheet
[v1-11] 2015-Jan-28
Page 23
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AS1310 −
Pack age Drawings & Mark ings
Package Drawings & Markings
The device is available in a TDFN (2x2) 8-pin package.
Figure 25:
Drawings and Dimensions
X X X
A2
Green
RoHS
Note(s) and/or Footnote(s):
1. Dimensioning & tolerancing conform to
ASME Y14.5M-1994
.
2. All dimensions are in millimeters. Angles are in degrees.
3. Coplanarity applies to the exposed heat slug as well as the terminal.
4. Radius on terminal is optional.
5. N is the total number of terminals.
Page 24
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Symbol Min
D2
E2 aaa bbb ccc ddd eee fff
N
E e b
D
A
A1
A3
L
0.51
0.00
0.225
0.18
-
-
-
1.45
0.75
-
-
Nom
1.60
0.90
0.15
0.10
0.10
0.05
0.08
0.10
8
0.55
0.02
0.15 REF
0.325
0.25
2.00 BSC
2.00 BSC
0.50 BSC
Max
0.60
0.05
0.425
0.30
-
-
-
-
1.70
1.00
-
-
ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Ordering & Contact Information
Ordering & Contact Information
The device is available as the standard products shown in
Figure 26:
Ordering Information
Ordering Code Marking Output
AS1310-BTDT-18
AS1310-BTDT-20
AS1310-BTDT-25
AS1310-BTDT-27
AS1310-BTDT-30
A2
A8
A9
A7
A6 tbd tbd
1.8V
2.0V
2.5V
2.7V
3.0V
3.3V
tbd
Description
Ultra Low Quiescent
Current,
Hysteretic DC-DC
Step-Up Converter
Delivery
Form
Package
Tape and Reel TDFN (2x2) 8-pin
Tape and Reel TDFN (2x2) 8-pin
Tape and Reel TDFN (2x2) 8-pin
Tape and Reel TDFN (2x2) 8-pin
Tape and Reel TDFN (2x2) 8-pin
Tape and Reel TDFN (2x2) 8-pin
Tape and Reel TDFN (2x2) 8-pin
Note(s) and/or Footnote(s):
1. On request
2. Non-standard devices are available between 1.8V and 3.3V in 50mV steps.
Buy our products or get free samples online at: www.ams.com/ICdirect
Technical Support is available at: www.ams.com/Technical-Support
Provide feedback about this document at: www.ams.com/Document-Feedback
For further information and requests, e-mail us at: [email protected]
For sales offices, distributors and representatives, please visit: www.ams.com/contact
Headquarters
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten
Austria, Europe
Tel: +43 (0) 3136 500 0
Website: www.ams.com
ams Datasheet
[v1-11] 2015-Jan-28
Page 25
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AS1310 −
RoHS Compliant & ams Green Statement
RoHS Compliant & ams Green
Statement
RoHS:
The term RoHS compliant means that ams AG products fully comply with current RoHS directives. Our semiconductor products do not contain any chemicals for all 6 substance categories, including the requirement that lead not exceed
0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, RoHS compliant products are suitable for use in specified lead-free processes.
ams Green (RoHS compliant and no Sb/Br):
ams Green defines that in addition to RoHS compliance, our products are free of Bromine (Br) and Antimony (Sb) based flame retardants
(Br or Sb do not exceed 0.1% by weight in homogeneous material).
Important Information:
The information provided in this statement represents ams AG knowledge and belief as of the date that it is provided. ams AG bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. ams AG has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. ams AG and ams AG suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
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ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Copyrights & Disclaimer
Copyrights & Disclaimer
Copyright ams AG, Tobelbader Strasse 30, 8141
Unterpremstaetten, Austria-Europe. Trademarks Registered. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner.
Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its General Terms of
Trade. ams AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein. ams AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by ams AG for each application. This product is provided by ams AG “AS IS” and any express or implied warranties, including, but not limited to the implied warranties of merchantability and fitness for a particular purpose are disclaimed.
ams AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other services.
ams Datasheet
[v1-11] 2015-Jan-28
Page 27
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AS1310 −
Document Status
Document Status
Document Status
Product Preview
Preliminary Datasheet
Datasheet
Datasheet (discontinued)
Product Status
Pre-Development
Pre-Production
Production
Discontinued
Definition
Information in this datasheet is based on product ideas in the planning phase of development. All specifications are design goals without any warranty and are subject to change without notice
Information in this datasheet is based on products in the design, validation or qualification phase of development.
The performance and parameters shown in this document are preliminary without any warranty and are subject to change without notice
Information in this datasheet is based on products in ramp-up to full production or full production which conform to specifications in accordance with the terms of ams AG standard warranty as given in the General Terms of
Trade
Information in this datasheet is based on products which conform to specifications in accordance with the terms of ams AG standard warranty as given in the General Terms of
Trade, but these products have been superseded and should not be used for new designs
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ams Datasheet
[v1-11] 2015-Jan-28
AS1310 −
Revision Information
Revision Information
Changes from 1-10 (2014-Nov-11) to current revision 1-11 (2015-Jan-28)
Updated Figure 18
Updated Figures 19 & 20
Note(s) and/or Footnote(s):
1. Page and figure numbers for the previous version may differ from page and figure numbers in the current revision.
2. Correction of typographical errors is not explicitly mentioned.
Page
ams Datasheet
[v1-11] 2015-Jan-28
Page 29
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Content Guide
AS1310 −
Content Guide
1 General Description
1 Key Benefits & Features
2 Applications
3 Pin Assignment
4 Absolute Maximum Ratings
5 Electrical Characteristics
7 Typical Operating Characteristics
12 Detailed Description
12 Hysteretic Boost Converter
12 Input Loop Timing
15 Inductor Choice Example
15 Output Loop Timing
16 Input Capacitor Selection
17 Output Capacitor Selection
17 Summary
18 Application Information
18 AS1310 Features
19 Power-OK and Low-Battery-Detect Functionality
21 Thermal Shutdown
21 Always ON Operation
22 Component Selection
22 Inductor Selection
23 Capacitor Selection
23 Layout Considerations
24 Package Drawings & Markings
25 Ordering & Contact Information
26 RoHS Compliant & ams Green Statement
27 Copyrights & Disclaimer
28 Document Status
29 Revision Information
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ams Datasheet
[v1-11] 2015-Jan-28
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