AS1312

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
Features
Ideal for single Li-Ion battery powered applications
Wide Input Voltage Range (0.7V to 5.0V)
Feedthrough mode when VIN > V OUT
Extended battery life
High Efficiency up to 94%
Less Power Consumption
Low Quiescent Current of typ. 1uA
Low Shutdown Current of less than 100nA
Supports a variety of end applications
Fixed output voltage range (2.5V to 5.0V)
Peak Output Current of 200mA
Output Disconnect in shutdown
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 1
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AS1312 − General Description
Benefits
Features
Over – temperature protection and shutdown
Integrated temperature monitoring
Early power-fail warning
Low battery detection
Cost effective, small package
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 for reference are
shown below:
Figure 2:
AS1312 Block Diagram
AS1312
VIN 0.7V to 5.0V
LX
Zero
Crossing
Detector
L1 6.8µF
VOUT
VOUT 2.5V to 5.0V
COUT
22µF
LBI
R3
100 k
+
ON
OFF
EN
VIN
100mV
LBO
+
-
CIN
22µF
-
Startup
Circuitry
Driver &
Control
Logic
0.6V
92.5% VREF
+
Imax
Detection
-
REF
VREF
GND
Page 2
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CREF
100nF
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Pin Assignments
Pin Assignments
Figure 3:
Pinout (Top View)
LBI
1
GND
2
8
VIN
7
EN
6
LBO
Pin A1
indicator
AS1312
TDFN 8-pin 2x2mm
LX
VOUT
Exposed pad: GND
3
4
9
5
A1
LBI
A2
GND
A3
LX
A4
VOUT
B1
VIN
B2
EN
B3
LBO
B4
REF
REF
Figure 4:
Pin Description
Pin Number
Pin Name
Description
WL-CSP
TDFN
A1
1
LBI
A2
2
GND
A3
3
LX
A4
4
VOUT
B4
5
REF
Reference Pin. Connect a 100nF ceramic capacitor to this pin.
B3
6
LBO
Low Battery Comparator Output. Open-drain output.
B2
7
EN
Enable Pin. Logic controlled shutdown input.
1 = Normal operation;
0 = Shutdown; shutdown current <100nA.
B1
8
VIN
Battery Voltage Input. Decouple VIN with a ceramic capacitor as
close as possible to VIN and GND.
-
9
NC
Exposed Pad. This pad is not connected internally. Can be left
floating or connect to GND to achieve an optimal thermal
performance.
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
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.
Page 3
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AS1312 − 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.
Absolute Maximum Ratings
Figure 5:
Absolute Maximum Ratings
Parameter
Min
Max
Unit
Comments
Electrical Parameters
VIN, VOUT, EN, LBI, LBO to
GND
-0.3
7
V
LX, REF to GND
-0.3
VOUT + 0.3
V
Input Current
(latch-up immunity)
-100
100
mA
Norm: JEDEC 78
Electrostatic Discharge
Electrostatic Discharge HBM
±2
kV
Norm: MIL 883 E method 3015
Temperature Ranges and Storage Conditions
WL-CSP
97
TDFN
60
θJA(1)
Thermal
Resistance
TAMB
Operating Temperature
TJ
Junction
Temperature
ºC/W
-40
85
ºC
WL-CSP
125
ºC
TDFN
150
ºC
-55
150
ºC
for 8-pin (2x2) TDFN
-55
125
ºC
for 8-pin WL-CSP
Storage Temperature Range
Norm IPC/JEDEC J-STD-020(2)
WL-CSP
TBODY
Package Body
Temperature
ºC
85
%
TDFN
Humidity non-condensing
Page 4
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260
5
Norm IPC/JEDEC J-STD-020(2)
The lead for Pb-free leaded packages is
matte tin (100% Sn)
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Electrical Characteristics
Parameter
Moisture
Sensitivity Level
Min
Max
Unit
WL-CSP
Comments
Represents an unlimited floor life time
1
TDFN
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
TAMB = 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
Min
Typ
Max
Unit
5.0
V
Input
VIN
Input Voltage Range
Minimum Startup Voltage
0.7
TAMB = 25°C
0.9
V
Regulation
VOUT
Output Voltage Range
Output Voltage Tolerance
VOUT Lockout Threshold (1)
2.5
5.0
V
ILOAD = 0mA to 10mA,
TAMB = 25°C
-2
2
%
ILOAD = 0mA to 10mA
-4
4
%
ILOAD = 0mA to 30mA,
TAMB = -20°C to 60°C
-2
2
%
Rising Edge
2.45
V
Operating Current
Quiescent Current VIN
VOUT = 1.02xVOUTNOM,
REF = 0.99xVOUTNOM,
TAMB = 25°C
Quiescent Current VOUT
VOUT = 5V, No load,
TAMB = 25°C
Shutdown Current
TAMB = 25ºC
IQ
IQSHDN
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
0.7
1
100
nA
1.3
μA
100
nA
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AS1312 − Electrical Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
Switches
NMOS
PMOS
NMOS maximum on-time
IPEAK
0.4
Ω
0.45
Ω
VOUT = 5V
RON
3.3
Peak current limit
4.0
4.6
400
Zero crossing current
5
20
μs
mA
35
mA
Enable, Reference
VENH
EN input voltage ‘high’
VENL
EN input voltage ‘low’
IEN
EN input bias current
IREF
REF input bias current
0.7
V
0.1
V
EN = 5V, TAMB = 25°C
100
nA
REF = 0.99xVOUTNOM,
TAMB = 25°C
100
nA
0.63
V
Low Battery & Power-OK
VLBI
LBI threshold
Falling edge
0.57
LBI hysteresis
0.6
25
ILBI
LBI leakage current
LBI ≤ VIN or VOUT (which ever
is higher), TAMB = 25°C
VLBO
LBO voltage low (2)
ILBO = 1mA
ILBO
LBO leakage current
TAMB = 25°C
Power-OK threshold
LBI = 0V, Falling Edge
5
87
91
mV
100
nA
20
mV
100
nA
95
%
Thermal Protection
Thermal shutdown (3)
10°C Hysteresis
150
°C
Caution: Do not apply full load current until the device output > 2.5V
Note(s) and/or Footnote(s):
1. The regulator is in startup mode until this voltage is reached.
2. LBO goes low in startup mode as well as during normal operation if,
(i) The voltage at the LBI pin is lower than LBI threshold.
(ii) The voltage at the LBI pin is below 0.1V (connected to GND) and VOUT is below 92.5% of its nominal value.
3. Further switching is inhibited.
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ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Typical Operating Characteristics
Typical Operating
Characteristics
V OUT = 5.0V, TAMB = 25°C, unless otherwise specified.
Figure 7:
Efficiency vs. Output Current
100
L1: LPS4018-682M
90
Efficiency (%)
80
70
60
50
40
30
Vin = 0.9V
20
Vin = 1.5V
10
Vin = 4.0V
Vin = 2.5V
0
0.001
0.01
0.1
1
10
100
Output Current (mA)
Figure 8:
Efficiency vs. Output Current
100
L1: XPL2010-682M
90
Efficiency (%)
80
70
60
50
40
30
Vin = 0.9V
Vin = 1.5V
20
Vin = 2.5V
10
0
0.001
Vin = 4.0V
0.01
0.1
1
10
100
Output Current (mA)
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 7
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AS1312 − Typical Operating Characteristics
Figure 9:
Efficiency vs. Input Voltage
100
L1: XPL2010-682M
90
Efficiency (%)
80
70
60
50
40
30
Iout = 1mA
Iout=10mA
20
Iout=50mA
10
Iout=100mA
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Input Voltage (V)
Figure 10:
Maximum Output Current vs. Input Voltage
200
Output Current (mA) .
175
150
125
100
75
50
25
0
1
1.5
2
2.5
3
3.5
4
4.5
Input Voltage (V)
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[v1-18] 2014-Dec-15
AS1312 − Typical Operating Characteristics
Figure 11:
Start-up Voltage vs. Output Current
1
0.95
Start-up Voltage (V)
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)
100mV/Div
VOUT (AC)
ILX
200mA/Div
VLX
2V/Div
Figure 12:
Output Voltage Ripple; VIN= 2V, Rload= 100Ω
5µs/Div
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 9
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AS1312 − Detailed Description
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 VOUT (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 Figure 15 will support many
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 AS1312,
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.
Page 10
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ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Detailed Description
Figure 13:
Simplified Boost DCDC Architecture
L1
SW2
VIN
VOUT
Q
CIN
SW1
Q
FB
COUT
RLOAD
IPK
GND
0V
0V
On time of the power switch (Faraday’s Law) is given by:
(EQ1)
LI PK
T ON = ------------------------------------------------------------------ sec [volts, amps, ohms, Henry]
V IN – ( I PK R SW1 + I PK R L1 )
Applying Min and Max values and neglecting the resistive
voltage drop across L1 and SW1;
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
(EQ2)
TON _ MIN =
(EQ3)
TON _ MAX =
LMIN I PK _ MIN
VIN _ MAX
LMAX I PK _ MAX
V IN _ MIN
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AS1312 − Detailed Description
Figure 14:
Simplified Voltage and Current Waveforms
V
0.99VOUT_NOM
VOUT Ripple
VOUT
B
VIND_TOFF
B
VIN
VIND_TON
C
D
A
C
D
0
T
TOFF
IL
TWAIT
TON
SW1_on
SW2_off
TOFF
TWAIT
IPK
0
SW2_on
SW1_off
T
T
T
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 14 shows this graphically with the shaded
segments marked “A & B”. Re-arranging (EQ 4):
(EQ5)
V OUT – V IN
T ON
------------ = ---------------------------T OFF
V IN
The time segment called T WAIT in Figure 14 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.
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ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Detailed Description
Inductor Choice Example
For the AS1312 VIN_MIN = 0.9V, V OUT_MAX = 3.3V, (EQ 5) gives
TON=2.66TOFF.
Let the maximum operating on-time = 1μs.
Note that this is shorter than the minimum limit on-time of
3.6μs. Therefore from (EQ 5), TOFF = 0.376μs. Using (EQ 3), 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 VIN.
Energy stored during the on time is given by:
(EQ6)
2
E = 0.5L ( I PK ) Joules (Region A in Figure 14)
If the overall time period (TON + TOFF ) is T, the power taken from
the input is:
2
(EQ7)
0.5L ( I PK )
P IN = --------------------------T
Watts
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.
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 13
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AS1312 − Detailed Description
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 off. 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
Figure 14):
(EQ8)
T
I
PK OFF
- ------------P REGION_C = V IN -------
2
T
Output power is also composed of the inductor component
(Region B in Figure 14), neglecting efficiency loss:
(EQ9)
0.5L ( I
T
)
2
PK
P REGION_B = --------------------------
Total power delivered to the load is the sum of (EQ 8) and (EQ 9):
2
(EQ10)
I PK T OFF 0.5L ( I PK )
P TOTAL = V IN -------- ------------- + --------------------------2 T
T
From (EQ 3) (using nominal values) peak current is given by:
(EQ11)
T ON V IN
I PK = ------------------L
Substituting (EQ 11) into (EQ 10) and re-arranging:
2
(EQ12)
V IN T ON
P TOTAL = ---------------------- ( 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:
2
(EQ13)
Page 14
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V OUT
P OUT = ----------------R LOAD
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Detailed Description
Combining (EQ 12) and (EQ 13):
2
(EQ14)
2
V IN T ON
V OUT
- ( 0.9T )η
---------------- = --------------------R LOAD
2TL
Symbol η reflects total energy loss between input and output
and is approximately 0.8 for these calculations. Use (EQ 14) to
plot duty cycle (TON/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)
I PEAK T ON
C IN = ------------------------V RIPPLE
Using TON = 1μs, and I PEAK = 400mA (typ), and V RIPPLE = 50mV,
EQ 15 yields:
C IN = 8.0μF
Nearest preferred would be 10μF.
(EQ16)
V PK _ RIPPLE _ ESR = I PK R ESR
Typically, the ripple due to ESR is not dominant. ESR for the
recommended capacitors (Murata GMR), ESR = 5mΩ to 10mΩ.
For the AS1312, maximum peak current is 400mA. Ripple due
to ESR is 2.0mV to 4.0mV.
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.
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 15
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AS1312 − Detailed Description
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 14) and on-time (Region A in Figure 14) of the power
switch.
(EQ17)
COUT =
I LOAD (TON + TWAIT )
(1 − 0.99)VOUT _ 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 AS1312. Use (EQ 3) to
calculate inductor value.
Use (EQ 5) to determine off-time.
Use (EQ 6) to check that power delivery matches load
requirements assume 70% conversion efficiency.
Use (EQ 13) 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 (EQ 6) or (EQ 13), and use (EQ 16) to find
the value.
Page 16
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ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Application Information
The AS1312 is available with fixed output voltages from 2.5V to
5.0V in 50mV steps.
Application Information
Figure 15:
Typical Application Diagram
VIN
0.7V to 5.0V
L1
6.8µH
LX
LBO
Low Battery
Detect
AS131 2
CIN
22µF
ON
VIN
OUT
LBI
REF
EN
GND
V OUT
2.5V to 5.0V
CREF
100 nF
COUT
22µF
OFF
0V
AS1312 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 VIN or V OUT, as long as it is
limited to less than 5.0V.
Output Disconnect
During shutdown VOUT is going to 0V and no current from the
input source is running through the device.
Feedthrough Mode
If the input voltage is higher than the output voltage (and the
AS1312 is enabled) the supply voltage is connected to the load
through the device. To guarantee a proper function of the
AS1312 it is not allowed that the supply exceeds the maximum
allowed input voltage (5.0V).
In this feedthrough mode the quiescent current is 35μA (typ.).
The device goes back into step-up mode when the output
voltage is 4% (typ.) below V OUTNOM.
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 17
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AS1312 − 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 100kΩ
resistor is perfect for most applications see Figure 17.
For the circuit shown in the left of Figure 16, 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)
V IN
R 1 = R 2 ⋅  ----------- – 1
 V LBI

Where: VLBI is 0.6V
Figure 16:
Typical Application with Adjustable Battery Monitoring
VIN
0.7V to 5.0V
L1
6.8µH
LX
LBO
Low Battery
Detect
AS131 2
CIN
22µF
ON
VIN
OUT
LBI
REF
EN
GND
V OUT
2.5V to 5.0V
CREF
100 nF
COUT
22µF
OFF
0V
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ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Application Information
Figure 17:
Typical Application with LBO Working as Power-OK
VIN
0.7V to 5.0V
L1
6.8µH
LX
LBO
Power OK
Output
AS131 2
CIN
22µF
ON
VIN
OUT
LBI
REF
EN
GND
V OUT
2.5V to 5.0V
CREF
100 nF
COUT
22µF
OFF
0V
Thermal Shutdown
To prevent the AS1312 from short-term misuse and overload
conditions the chip includes a thermal overload protection. To
block the normal operation mode all further switching is
inhibited for output voltage above V OUT lockout threshold. 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 AS1312 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.
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 19
Document Feedback
AS1312 − Application Information
Component Selection
Only four components are required to complete the design of
the step-up converter. The low peak currents of the AS1312
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
< 500mΩ DCR is recommended.
Figure 18:
Recommended Inductors
L
DCR
Current
Rating
Size in mm
(L/W/T)
ELLVEG6R8N
6.8uH
0.35Ω
0.58A
3x3x1
ELLVFG6R8MC
6.8uH
0.23Ω
0.6A
3x3x1.2
ELLVGG6R8N
6.8uH
0.23Ω
1A
3x3x1.5
LQH3NPN6R8MM0
6.8uH
0.24Ω
1A
3x3x1.4
LQH3NPN6R8NM0
6.8uH
0.24Ω
1A
3x3x1.4
LQH3NPN6R8MJ0
6.8uH
0.252Ω
0.85A
3x3x1.1
LQH3NPN6R8NJ0
6.8uH
0.252Ω
0.85A
3x3x1.1
LQH3NPN6R8MMR
6.8uH
0.186Ω
1.25A
3x3x1.1
VLS2012ET-6R8M
6.8uH
0.498
0.57A
2x2x1.2
VLS252015ET-6R8M
6.8uH
0.48
0.85A
2.5x2x1.5
VLS3010ET-6R8M
6.8uH
0.312
0.69A
3x3x1
VLS3012ET-6R8M
6.8uH
0.228
0.81A
3x3x1.2
VLS3015ET-6R8M
6.8uH
0.216
0.92A
3x3x1.5
LPS4018-682ML
6.8uH
0.15
1.2A
4x4x1.7
Part Number
Page 20
Document Feedback
Manufacturer
Panasonic
www.industrial.panasonic.com
Murata
www.murata.com
TDK
www.tdk.com
Coilcraft
www.coilcraft.com
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − 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. See table below for a list
of capacitors for input and output capacitor selection.
Figure 19:
Recommended Input and Output Capacitors
C
TC
Code
Rated
Voltage
Size in mm
(L/W/T)
GRM21BR60J226ME39L
22uF
X5R
6.3V
2x1.25x1.25
GRM31CR61A226ME19L
22uF
X5R
10V
3.2x1.6x1.6
12066D226KAT_A
22uF
X5R
6.3V
3.2x1.6x1.78
1210ZD226KAT_A
22uF
X5R
10V
3.2x1.6x1.78
1210YD226KAT_A
22uF
X5R
16V
3.2x1.6x1.78
C2012X5R0J226K/1.25
22uF
X5R
6.3V
2x1.2x1.25
C2012X5R1A226K/1.25
22uF
X5R
10V
2x1.2x1.25
C2012X5R1C226K
22uF
X5R
16V
2x1.2x1.25
Part Number
Manufacturer
Murata
www.murata.com
AVX
www.avx.com
TDK
www.tdk.com
On the pin REF a 100nF capacitor with an
Insulation resistance >1GΩ is recommended.
Figure 20:
Recommended Capacitors for REF
Part Number
C
TC
Code
Insulation
Resistance
Rated
Voltage
Dimensions
(L/W/T)
Manufacturer
GRM188R71C104KA01
100nF
X7R
>5GΩ
16V
0603, T=0.8mm
Murata
www.murata.com
Layout Considerations
Relatively high peak currents of 400mA (typ) circulate during
normal operation of the AS1312. 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 15, the input loop formed by C1, VIN
and GND pins should be minimized. Similarly, the output loop
formed by C2, VOUT 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, Confidential
[v1-18] 2014-Dec-15
Page 21
Document Feedback
AS1312 − Package Drawings & Mark ings
Package Drawings & Markings
The device is available in a 8-pin (2x2) TDFN and 8-pin WL-CSP
package.
Figure 21:
8-pin (2x2) TDFN Marking
XXX
YY
Figure 22:
8-pin WL-CSP Marking
YY
XXXX
Figure 23:
Packaging Code
XXX
XXXX
YY
Tracecode for TDFN
Tracecode for WL-CSP
Marking
Page 22
Document Feedback
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Package Drawings & Markings
Figure 24:
8-pin (2x2) TDFN Drawings and Dimensions
Green
RoHS
s
Symbol
Min
A
A1
A3
L
b
D
E
e
D2
E2
aaa
bbb
ccc
ddd
eee
fff
N
0.51
0.00
Nom
Max
0.55
0.60
0.02
0.05
0.15 REF
0.225
0.325
0.425
0.18
0.25
0.30
2.00 BSC
2.00 BSC
0.50 BSC
1.45
1.60
1.70
0.75
0.90
1.00
0.15
0.10
0.10
0.05
0.08
0.10
8
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.
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 23
Document Feedback
AS1312 − Package Drawings & Mark ings
Figure 25:
8-pin WL-CSP Drawings and Dimensions
Die size excluding the scribeline: 1570 x 790µm
Dimensions
Green
RoHS
Package x-dimension
Package y-dimension
Package height
Bump height
Bump Diameter
Die thickness
Min [μm] Nom [μm] Max [μm]
1595
815
470
180
250
270
1615
835
500
200
270
275
1635
855
530
220
290
280
Note(s) and/or Footnote(s):
1. ccc Coplanarity.
2. All dimensions are in μm.
3. “Bottom view” and “top trough view” values indicate the die dimensions without scribe lines. The “die size after cutting” values
gives the package dimensions with tolerance.
Page 24
Document Feedback
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Ordering & Contact Information
Ordering & Contact Information
The device is available as the standard products listed below.
Figure 26:
Ordering Information
Marking
VOUT
AS1312-BTDT-50
BE
AS1312-BTDT-33
AS1312-BTDT-30
Ordering Code
Description
Delivery Form
Package
5.0V
Tape and Reel
8-pin (2x2) TDFN
BX
3.3V
Tape and Reel
8-pin (2x2) TDFN
BY
3.0V
Tape and Reel
8-pin (2x2) TDFN
Tape and Reel
8-pin (2x2) TDFN
Tape and Reel
8-pin WL-CSP
Tape and Reel
8-pin WL-CSP
Ultra Low
Quiescent
Current,
Hysteretic DC-DC
Step-up Converter
AS1312-BTDM-27
C1
2.7V
AS1312-BWLT-50
BF
5.0V
AS1312-BWLT-45
BQ
4.5V
AS1312-BWLT-33
CO
3.3V
Tape and Reel
8-pin WL-CSP
AS1312 (1)
tbd
xx
Tape and Reel
tbd
Note(s) and/or Footnote(s):
1. Non-standard devices from 2.5V to 5.0V are available in 50mV steps.
The above figure shows the ordering codes for Tape & Reel
deliveries (suffix T in the ordering code). It is also possible to
have all the variants on mini reels, when the ordering codes are
AS1312-BTDM-xx or AS1312-BWLM (where suffix M stands for
mini reel). The components are the same in both reel sizes.
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, Confidential
[v1-18] 2014-Dec-15
Page 25
Document Feedback
AS1312 − 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.
Page 26
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ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − 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, Confidential
[v1-18] 2014-Dec-15
Page 27
Document Feedback
AS1312 − Document Status
Document Status
Document Status
Product Preview
Preliminary Datasheet
Datasheet
Datasheet (discontinued)
Page 28
Document Feedback
Product Status
Definition
Pre-Development
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
Pre-Production
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
Production
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
Discontinued
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
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
AS1312 − Revision Information
Revision Information
Changes from 1-16 (2014-Sep-01) to current revision 1-18 (2014-Dec-15)
Updated Package Drawings & Markings section
Page
24
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.
ams Datasheet, Confidential
[v1-18] 2014-Dec-15
Page 29
Document Feedback
AS1312 − Content Guide
Content Guide
Page 30
Document Feedback
1
1
2
2
General Description
Key Benefits & Features
Applications
Block Diagram
3
4
5
7
Pin Assignments
Absolute Maximum Ratings
Electrical Characteristics
Typical Operating Characteristics
10
10
10
13
14
15
16
16
Detailed Description
Hysteretic Boost Converter
Input Loop Timing
Inductor Choice Example
Output Loop Timing
Input Capacitor Selection
Output Capacitor Selection
Summary
17
17
17
17
17
18
19
20
20
21
21
Application Information
AS1312 Features
Shutdown
Output Disconnect
Feedthrough Mode
Power-OK and Low-Battery-Detect Functionality
Thermal Shutdown
Component Selection
Inductor Selection
Capacitor Selection
Layout Considerations
22
25
26
27
28
29
Package Drawings & Markings
Ordering & Contact Information
RoHS Compliant & ams Green Statement
Copyrights & Disclaimer
Document Status
Revision Information
ams Datasheet, Confidential
[v1-18] 2014-Dec-15