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Surface Mount Varistors
Multilayer Transient Voltage Suppressor
MLE Varistor Series
The MLE Series family of Transient Voltage Suppression devices are based
on the Littelfuse Multilayer fabrication technology. These components are
designed to suppress ESD events, including those specified in IEC 61000-
4-2 or other standards used for Electromagnetic Compliance testing. The
MLE Series is typically applied to protect integrated circuits and other
components at the circuit board level operating at 18VDC, or less.
The fabrication method and materials of these devices result in capaci-
tance characteristics suitable for high frequency attenuation/low-pass
filter circuit functions, thereby providing suppression and filtering in a
single device.
The MLE Series is manufactured from semiconducting ceramics and is sup-
plied in a leadless, surface mount package. The MLE Series is compatible
with modern reflow and wave soldering procedures.
Littelfuse Inc. manufactures other Multilayer Series products. See the ML
Series data sheet for higher energy/peak current transient applications. See
the AUML Series for automotive applications and the MLN Quad Array. For
high speed applications see the MHS series.
3
SURFACE MOUNT
VARISTORS
133
Features
• Rated for ESD (IEC-61000-4-2)
• Characterized for Impedance and Capacitance
•-55
o
C to +125
o
C Operating Temperature Range
• Leadless 0402, 0603, 0805, and 1206 sizes
• Operating Voltages up to 18VM(DC)
• Multilayer Ceramic Construction Technology
Applications
• Protection of Components and Circuits Sensitive to ESD Transients
Occurring on Power Supplies, Control and Signal Lines
• Suppression of ESD Events Such as Specified in IEC-61000-4-2 or
MIL-STD-883C Method-3015.7, for Electromagnetic Compliance (EMC)
• Used in Mobile Communications, Computer/EDP Products, Medical
Products, Hand Held/Portable Devices, Industrial Equipment,
Including Diagnostic Port Protection and I/O Interfaces
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Surface Mount Varistors
Multilayer Transient Voltage Suppressor
MLE Varistor Series
Absolute Maximum Ratings
For ratings of individual members of a series, see device ratings and specifications table.
Continuous:
MLE SERIES
Steady State Applied Voltage:
DC Voltage Range (VM(DC)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
≤18
Operating Ambient Temperature Range (TA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to + 125
Storage Temperature Range (TSTG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to + 150
UNITS
V
C
O
C
O
Device Ratings and Specifications
MAX CONTINUOUS
WORKING VOLTAGE
-55
o
C TO 125
o
C
(NOTE 1)
V
M(DC)
PART
NUMBER
PERFORMANCE SPECIFICATIONS (25
o
C)
NOMINAL
VOLTAGE
V
NOM
AT
1mA DC
MAX
(V)
28
MAXIMUM CLAMPING
VOLTAGE AT SPECIFIED
CURRENT (8/20µS)
MAXIMUM
ESD CLAMP VOLTAGE (NOTE 2)
Vc
(NOTE 3)
8kV CONTACT
Clamp
(V)
<125
(NOTE 4)
15kV AIR
Clamp
(V)
<160
TYPICAL
CAPACITANCE
AT 1MHz
MAXIMUM
LEAKAGE
I
L MAX
AT APPLIED
VOLTAGE
(V)
18
MIN (V)
22
(V)
50
at 10A
( pF)
<40
(
µA)
0.1
0.3
2
10
V
DC
3.5
5.5
15
18
3.5
5.5
15
18
3.5
5.5
15
18
3.5
5.5
15
18
3.5
5.5
15
18
3.5
5.5
15
18
NEW
V18MLE0402
V18MLE0603
18
22
28
50
at 10A
<75
<85
<100
0.1
0.3
5.0
25
V18MLE0603L
18
22
28
50
at 10A
<100
<140
<60
0.1
0.3
5.0
25
V18MLE0805
18
22
28
50
at 10A
<70
<75
<500
0.2
0.5
5.0
25
V18MLE0805L
18
22
28
50
at 10A
<75
<135
<100
0.2
0.5
5.0
25
V18MLE1206
18
22
28
50
at 10A
<65
<65
<1700
0.5
1.0
5.0
25
NOTES:
1. For applications of 18V
DC
or less. Higher voltages available, contact your Littelfuse Sales Representative.
2. Tested with IEC-61000-4-2 Human Body Model (HBM) discharge test circuit.
3. Direct discharge to device terminals (IEC preferred test method).
4. Corona discharge through air (represents actual ESD event).
5. Capacitance may be customized, contact your Littelfuse Sales Representative.
134
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Surface Mount Varistors
Multilayer Transient Voltage Suppressor
MLE Varistor Series
Typical Performance Curves
For applications exceeding 125
0
C ambient temperature, the peak surge
current and energy ratings must be reduced as shown in Figure 1.
30
NOMINAL VOLTAGE AT 1mADC
100
PERCENT OF RATED VALUE
25
20
80
60
3
10
5
0
40
20
0
-55
50
60
70
80
90
100
110 120
130 140 150
1
10
100
CURRENT (A)
1000
10000
AMBIENT TEMPERATURE (
o
C)
FIGURE 1. PEAK CURRENT AND ENERGY DERATING CURVE
FIGURE 2. NOMINAL VOLTAGE STABILITY TO MULTIPLE
ESD IMPULSES (8KV CONTACT DISCHARGES
PER IEC 61000-4-2)
30
25
VARISTOR VOLTAGE (V)
20
15
10
5
10
0.0001
0.001
0.01
0.1
1
NUMBER OF PULSES
125
O
25
O
100
-0402
10
-0603
-0805
IMPEDANCE (Z)
1
-1206
85
O
0.1
FIGURE 3. STANDBY CURRENT AT NORMALIZED VARISTOR
VOLTAGE AND TEMPERATURE
0.01
10
100
1000
FREQUENCY (MHz)
10000
FIGURE 4. IMPEDANCE (Z) vs FREQUENCY
TYPICAL CHARACTERISTIC
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SURFACE MOUNT
VARISTORS
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Surface Mount Varistors
Multilayer Transient Voltage Suppressor
MLE Varistor Series
Soldering Recommendations
TEMPERATURE (
o
C)
250
MAXIMUM
TEMPERATURE 222
o
C
200
40-80
SECONDS
ABOVE 183
o
C
RAMP RA
TE
<2
o
C/s
100
PREHEAT DWELL
50
PREHEAT ZONE
The principal techniques used for the soldering of components in surface
mount technology are Infrared (IR) re-flow, vapour phase re-flow, and
wave soldering. When wave soldering, the MLE suppressor is attached
to the circuit board by means of an adhesive. The assembly is then
placed on a conveyor and run through the soldering process to contact
the wave. With IR and vapour phase re-flow, the device is placed in a
solder paste on the substrate. As the solder paste is heated, it reflows
and solders the unit to the board.
The recommended solder for the MLE suppressor is a 62/36/2
(Sn/Pb/Ag), 60/40 (Sn/Pb), or 63/37 (Sn/Pb). Littelfuse also
recommends an RMA solder flux.
Wave soldering is the most strenuous of the processes. 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. For 0402 size devices,
IR re-flow is recommended.
When using a reflow process, care should be taken to ensure that the
MLE chip is not subjected to a thermal gradient steeper than 4 degrees
per second; the ideal gradient being 2 degrees per second. During the
soldering process, preheating to within 100 degrees of the solder’s peak
temperature is essential to minimize thermal shock. Examples of the
soldering conditions for the MLE series of suppressors are given in the
tables below.
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 the solder
process and subjected to cleaning solvents at room temperature. The
boards must be allowed to cool gradually to less than 50
o
C before cleaning.
150
0
0
0.5
1.0
1.5
2.0
2.5
TIME (MINUTES)
3.0
3.5
4.0
FIGURE 5. REFLOW SOLDER PROFILE
300
MAXIMUM WAVE 260
o
C
250
TEMPERATURE (
o
C)
200
150
SECOND PREHEAT
100
FIRST PREHEAT
50
0
0
Termination Options
Littelfuse offers two types of electrode termination finish for the
MLE series:
1. Silver/Platinum (standard) (Not 0402 and 0603 sizes)
2. Silver/Palladium (optional)
3. Nickel Barrier (optional for 0402-1210 package size)
(The ordering information section describes how to designate them.)
0.5
1.0
1.5
2.0
2.5
3.0
TIME (MINUTES)
3.5
4.0
4.5
FIGURE 6. WAVE SOLDER PROFILE
250
MAXIMUM
TEMPERATURE 222
o
C
200
TEMPERATURE (
o
C)
40-80
SECONDS
ABOVE 183
o
C
RAMP RA
TE
>50
o
C/s
100
PREHEAT ZONE
50
150
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
TIME (MINUTES)
FIGURE 7. VAPOR PHASE SOLDER PROFILE
136
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Surface Mount Varistors
Multilayer Transient Voltage Suppressor
MLE Varistor Series
Recommended Pad Outline
C
B
NOTE
3
NOTE: Avoid metal runs in this area.
TABLE 1: PAD LAYOUT DIMENSIONS
RECOMMENDED PAD SIZE DIMENSIONS
1206 SIZE DEVICE
DIMENSION
A
B
C
IN
0.160
0.065
0.040
MM
4.06
1.65
1.02
0805 SIZE DEVICE
IN
0.120
0.050
0.040
MM
3.05
1.27
1.02
0603 SIZE DEVICE
IN
0.100
0.030
0.035
MM
2.54
0.76
0.89
0402 SIZE DEVICE
IN
0.067
0.020
0.024
MM
1.70
0.51
0.61
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SURFACE MOUNT
VARISTORS
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