Littelfuse MLA Varistor Series - Manual (Page 5)

© 2013 Littelfuse, Inc. 43
Revised: December 16, 2013
Varistor Products
MLA Varistor Series
Surface Mount Multilayer Varistors (MLVs) > MLA Series
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/ML.html or MLA.html for current information.
MLA S
eries
Device Characteristics
At low current levels, the V-I curve of the multilayer
transient voltage suppressor approaches a linear (ohmic)
relationship and shows a temperature dependent effect.
At or below the maximum working voltage, the suppressor
is in a high resistance modex (approaching 10
6 Ω at its
maximum rated working voltage). Leakage currents at
maximum rated voltage are below 100µA, typically 25µA;
for 0402 size below 20µA, typically 5µA.
100%
1E -9 1E -8
SUPPRESSOR CURRENT (A DC )
10%
1E -7 1E -6 1E -5 1E -4 1E -3 1E -2
25 50 75 100 125 o C SUPPRESSOR
VO
LT
A
GE IN PERCENT OF
V
NOM
V
ALUE
AT
25
o
C (%)
FIGURE 10. TYPICAL TEMPERATURE DEPENDANCE OF THE CHARACTERISTIC
CURVE IN THE LEAKAGE REGION
o o o o
Clamping Voltage Over Temperature (V
C
at 10A)
100
10
20
V26MLA1206
40 60 80 100 120 140
TEMPERATURE ( o C)
CLAMPING
VO
LT
AG
E
(V)
V5.5MLA1206
0 -20 -40 -60
FIGURE 12. CLAMPING VOLTAGE OVER TEMPERATURE
(V
C
AT 10A)
Typical Temperature Dependance of the Haracteristic
Curve in the Leakage Region
Speed of Response
The Multilayer Suppressor is a leadless device. Its
response time is not limited by the parasitic lead
inductances found in other surface mount packages.
The response time of the Z
N
O dielectric material is less
than 1ns and the MLA can clamp very fast dV/dT events
such as ESD. Additionally, in "real world" applications,
the associated circuit wiring is often the greatest
factor effecting speed of response. Therefore, transient
suppressor placement within a circuit can be considered
important in certain instances.
GRAINS
DEPLETION
FIRED CERAMIC
DIELECTRIC
REGION
METAL
ELECTRODES
DEPLETION
REGION
METAL END
TERMINATION
FIGURE 11. MULTILAYER INTERNAL CONSTRUCTION
Multilayer Internal Construction
Energy Absorption/Peak Current Capability
Energy dissipated within the MLA Series is calculated
by multiplying the clamping voltage, transient current
and transient duration. An important advantage of the
multilayer is its interdigitated electrode construction within
the mass of dielectric material. This results in excellent
current distribution and the peak temperature per energy
absorbed is very low. The matrix of semiconducting grains
combine to absorb and distribute transient energy (heat)
(see Speed of Response). This dramatically reduces peak
temperature; thermal stresses and enhances device
reliability.
As a measure of the device capability in energy and peak
current handling, the V26MLA1206A part was tested with
multiple pulses at its peak current rating (3A, 8/20µs). At
the end of the test,10,000 pulses later, the device voltage
characteristics are still well within specification.
100
10
0
V26MLA1206
2000 4000 6000 8000 10000 12000
NUMBER OF PULSES
VO
LT
AG
E
FIGURE 13. REPETITIVE PULSE CAPABILITY
PEAK CURRENT = 3A
8/20 s DURATION, 30s BETWEEN PULSES
Repetitive Pulse Capability
Figure 10
Figure 11
Figure 12
Figure 13