V18MLA1210H Datasheet, PDF (7/11 Pages) Littelfuse – ML Varistor Series

Surface Mount Varistors
Multilayer Transient Voltage Surge Suppressors
RoHS _{ML Varistor Series}
Device Characteristics
100
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 (Figure 10). At or below the maximum
working voltage, the suppressor is in a high resistance mode (approach-
ing 10⁶Ω at its maximum rated working voltage). Leakage currents at
maximum rated voltage are below 50µA, typically 25µA; for 0402 size
below 10µA, typically 5µA.
100%
V26MLA1206
V5.5MLA1206
10%
1E^-9
25^o 50^o 75^o 100^o 125^oC
1E^-8
1E^-7
1E^-6
1E^-5
1E^-4
1E^-3
1E^-2
SUPPRESSOR CURRENT (A_DC)
FIGURE 10. TYPICAL TEMPERATURE DEPENDANCE OF THE CHARACTERISTIC
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 Zinc Oxide dielectric material is less
than 1 nanosecond and the ML 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.
FIRED CERAMIC
DIELECTRIC
10
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (^oC)
FIGURE 12. CLAMPING VOLTAGE OVER TEMPERATURE
(V_C AT 10A)
Energy Absorption/Peak Current Capability
Energy dissipated within the ML 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 semicon-
ducting grains combine to absorb and distribute transient energy (heat)
(Figure 11). 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 (150A, 8/20µs). At the end of the test, 10,000 pulses
later, the device voltage characteristics are still well within specification
(Figure 13).
100
PEAK CURRENT = 150A
8/20µs DURATION, 30s BETWEEN PULSES
V26MLA1206
METAL END
TERMINATION
METAL
ELECTRODES
DEPLETION
REGION
DEPLETION
REGION
GRAINS
FIGURE 11. MULTILAYER INTERNAL CONSTRUCTION
10
0
2000
4000
6000
8000
10000
12000
NUMBER OF PULSES
FIGURE 13. REPETITIVE PULSE CAPABILITY
174
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