Varistor Products
Surface Mount Multilayer Varistors (MLVs) > AUML Series
RoHS
AUML Varistor Series
Description
The AUML Series of Multilayer Transient Surge Suppressors
was specifically designed to suppress the destructive
transient voltages found in an automobile. The most common
transient condition results from large inductive energy
discharges. The electronic systems in the automobile, e.g.
antilock brake systems, direct ignition systems, engine
control, airbag control systems, wiper motor controls, etc.,
are susceptible to damage from these voltage transients and
thus require protection. The AUML transient suppressors
have temperature independent suppression characteristics
affording protection from -55ºC to 125ºC.
Size Table
Metric
EIA
3225
4532
1812
The AUML suppressor is manufactured from semiconducting
ceramics which offer rugged protection and excellent
transient energy absorption in a small package. The devices
are available in ceramic leadless chip form, eliminating lead
inductance and assuring fast speed of response to transient
surges. These Suppressors require significantly smaller
space and land pads than Silicon TVS diodes, offering greater
circuit board layout flexibility for the designer.
Also see the Littelfuse ML, MLN and MLE Series of
Multilayer Suppressors.
Applications
Features
inductive switching
or other transient
events such as
and surge voltage at
the circuit board level
components sensitive
transient voltage
protection for ICs
and transistors
electromagnetic
compliance of
end products
current capability
rated per SAE
Specification J1113
mount chip form
Inductance
industry standard
clamping
packaging assures
flammability rating
industry specifications
(See Also the MLE
many applications
ratings available
derating up to
125ºC ambient
Absolute Maximum Ratings
Continuous
Steady State Applied Voltage:
AUML Series
18
Units
V
J
V
O
C
O
C
%/
O
C
Transient:
A
STG
1.5 to 25
24.5
-55 to +125
Temperature Coefficient (
C
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any
other conditions above those indicated in the operational sections of this specification is not implied.
©2010 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/AUML.html for current information.
AUML Varistor Series
Revision: September 14, 2010
AUML Series
Varistor Products
Surface Mount Multilayer Varistors (MLVs) > AUML Series
Device Ratings and Specifications
Maximum Ratings (125
ºC
)
Maximum
Jump Start Load Dump
Continuous
Voltage
Energy
DC Voltage
(5 Min)
(10 Pulses)
V
V
W
(V)
18
18
V18AUMLA1812
18
18
update.
NOTES:
Part Number
Specifications (25
ºC
)
Nominal Varistor Voltage
Maximum
at 10mA
Standby Leakage
DC Test Current
(at 13V DC)
V
Min
V
Max
I
L
(V)
23
23
23
(V)
32
32
32
32
(μA)
Maximum Clamping
Voltage (V
C
) at
Test Current (8/20μs)
V
C
I
(V)
(A)
1.5
1.5
(V)
24.5
24.5
24.5
24.5
(J)
1.5
25
23
Current, Energy and Power Derating Curve
Peak Pulse Current Test Waveform for Clamping Voltage
device. Certain parameter ratings must be derated at high
temperatures as shown below.
PERCENT OF PEAK VALUE
times the number of pulses per second. The power so
developed must be within the specifications shown on the
100
50
0
O
1
T
T
1
TIME
100
PERCENT OF RATED VALUE
90
80
70
60
50
40
30
20
10
0
-55
50
60
70
80
90
100 110
120
130
140 150
Figure 2
1
T
2
Figure 1
AMBIENT TEMPERATURE (
o
C)
T
1
T
2
Example
8μs = T
1
μs
= T
2
μ
Maximum Leakage Current/Clamping Voltage Curve for
AUML Series at 25ºC
Typical V-I Characteristics of the V18AUMLA2220 at -40ºC,
25ºC, 85ºC and 125ºC
MAXIMUM LEAKAGE
MAXIMUM CLAMPING VOLTAGE
1210/1206
1812
2220
100
100
VOLTAGE
VOLTAGE
1210/1206
1812
2220
10
-40
o
C
25
o
C
10
85
o
C
125
o
C
1
1
10μA
100μA
1mA
Figure 3
AUML Varistor Series
100mA
10mA
CURRENT
1A
10A
100A
1μA
10μA
100μA
1mA
10mA
CURRENT
100mA
1A
10A
100A
1000A
Figure 4
©2010 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/AUML.html for current information.
Revision: September 14, 2010
Varistor Products
Surface Mount Multilayer Varistors (MLVs) > AUML Series
Temperature Effects
In the leakage region of the AUML suppressor, the device
and shows a temperature dependent affect. In this region
the suppressor is in a high resistance mode (approaching
at maximum rated voltage are in the microamp range.
of the AUML are virtually temperature independent.
the V-I characteristics of the AUML suppressor.
Load Dump Energy Capability
The very high energy absorption capability of the AUML
suppressor is achieved by means of a highly controlled
manufacturing process. This technology ensures that a
large volume of suppressor material, with an interdigitated
layer construction, is available for energy absorption in an
extremely small package. Unlike equivalent rated Silicon
TVS diodes, the entire AUML device volume is available to
automotive industry, with the most common one being that
recommended by the Society of Automotive Engineers,
specification #SAE J1113. Because of the diversity of these
that energy dissipated by the device itself, independent
handling capability serves as an excellent figure of merit for
even energy dissipation ensures that there are lower peak
AUML suppressor.
capability requirement is well within the ratings of all of the
There are a number of different size devices available in the
AUML Series, each one with a load dump energy rating,
which is size dependent.
Experience has shown that while the effects of a load dump
tranient is of real concern, its frequency of occurrence is
much less than thoe of low energy inductive spikes. Such
low energy inductive spikes may be generated as a result
blowing, etc. It is essential that the suppression technology
selected also has the capability to suppress such transients.
energy, which are applied to the devices. The reliability
information thus generated gives an indication of the
inherent capability of these devices. As an example of
all cases there has been little or no change in the device
Speed of Response
The clamping action of the AUML suppressor depends
on a conduction mechanism similar to that of other
slow response time often associated with transient
parasitic inductance in the package and leads of the
device and less dependent of the basic material (Silicon,
N
Multilayer Internal Construction
response time of any suppressor is its lead induc-tance.
The AUML suppressor is a surface mount device, with no
leads or external packaging, and thus, it has virtually zero
inductance. The actual response time of a AUML surge
suppressor is in the 1 to 5 ns range, more than sufficient
for the transients which are likely to be encountered in an
automotive environment.
©2010 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/AUML.html for current information.
Figure 5
AUML Varistor Series
Revision: September 14, 2010
AUML Series
the automobile is abruptly reduced. The worst case scenario
of this transient occurs when the battery is disconnected
while operating at full rated load. There are a number of
Varistor Products
Surface Mount Multilayer Varistors (MLVs) > AUML Series
AUML Load Dump Pulsing over a Temperature Range of
-55ºC to +125ºC
V(10mA)
2220 = 25J
1812 = 6J
1210 = 3J
Explanation of Terms
Maximum Continuous DC Working Voltage (*V
+
)
35
30
25
VOLTAGE
20
15
10
5
0
be applied, up to the maximum operating temperature
reference test point for leakage current and is always less
than the breakdown voltage of the device.
Load Dump Energy Rating *W
+
This is the actual energy the part is rated to dissipate
0
1
2
3
4
5
6
7
8
9
10
11
12
# OF LOAD DUMPS
Figure 6
Maximum Clamping Voltage *V
C+
Repetitive Load Dump Pulsing at Rated Energy
This is the peak voltage appearing across the suppressor
when measured at conditions of specified pulse current
μ
that the peak current and peak voltage may not necessarily
be coincidental in time.
Leakage Current *I
L+
In the nonconducting mode, the device is at a very
Ω at its rated working
system. The leakage current drawn at this level is very
low (<25μ
0
50
100
150
200
250
300
350
1,000
2,000
# OF LOAD DUMPS
35
30
25
VOLTAGE
20
15
10
5
0
V(10mA)
2220 = 25J
1812 = 6J
1210 = 3J
Figure 7
that, when operated up to its maximum temperature,
μA.
Nominal Voltage *V
+
Repetitive Energy Testing of V18AUMLA2220
at an Energy Level of 2 Joules
V AT 10mA
This is the voltage at which the AUML enters its
conduction state and begins to suppress transients.
In the automotive environment this voltage is
(V
100
VOLTAGE
V18AUMLA2220
10
1000
2000
3000
4000
5000
6000
7000
Figure 8
NUMBER OF PULSES
AUML Varistor Series
Revision: September 14, 2010
©2010 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/AUML.html for current information.
Varistor Products
Surface Mount Multilayer Varistors (MLVs) > AUML Series
Lead (Pb) Soldering Recommendations
The principal techniques used for the soldering of
Reflow Solder Profile
The termination option available for each solder technique is:
230
The recommended solder for the AUML suppressor is
To avoid the possibility of generating stresses due to
thermal shock, a preheat stage in the soldering process
is recommended, and the peak temperature of the solder
process should be rigidly controlled.
Figure 9
Wave Solder Profile
300
gradient steeper than 4 degrees per second; the ideal
TEMPERATURE (
o
C)
250
200
150
100
50
0
0.0
MAXIMUM WAVE 260
o
C
peak temperature is essential to minimize thermal shock.
Once the soldering process has been completed, it
is still necessary to ensure that any further thermal
shocks are avoided. One possible cause of thermal
shock is hot printed circuit boards being removed from
at room temperature. The boards must be allowed to
SECOND PREHEAT
FIRST PREHEAT
0.5
1.0
1.5
Figure 10
2.0
2.5
3.0
TIME (MINUTES)
3.5
4.0
4.5
Lead–free (Pb-free) Soldering Recommendations
Littelfuse offers the Nickel Barrier Termination finish for the
optimum Lead–free solder performance.
flux, but there is a wide selection of pastes and fluxes
available with which the Nickel Barrier parts should be
compatible.
The reflow profile must be constrained by the maximums
PREHEAT ZONE
Lead–free Re-flow Solder Profile
MAXIMUM TEMPERATURE 260˚C
20 - 40 SECONDS WITHIN 5˚C
RAMP RATE
<3˚C/s
60 - 150 SEC
> 217˚C
Note: the Lead–free paste, flux and profile were used for
evaluation purposes by Littelfuse, based upon industry
standards and practices. There are multiple choices of all
three available, it is advised that the customer explores the
optimum combination for their process as processes vary
considerably from site to site.
5.0
6.0
7.0
Figure 11
©2010 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/AUML.html for current information.
AUML Varistor Series
Revision: September 14, 2010
AUML Series
