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© 2017 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 09/14/17
Metal-Oxide Varistors (MOVs)
Axial Lead / Application Specific Varistors > MA Series
Should transients occur in rapid succession, the average power
dissipation required is simply the energy (watt-seconds) per
pulse times the number of pulses per second. The power so
developed must be within the specifications shown on the
Device Ratings and Specifications table for the specific device.
Furthermore, the operating values need to be derated at high
temperatures as shown above. Because varistors can only
dissipate a relatively small amount of average power they are,
therefore, not suitable for repetitive applications that involve
substantial amounts of average power dissipation.
Power Dissipation Ratings
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE
100
90
80
70
60
50
40
30
20
10
0
-55 50 60 70 80 90 100110 120130 140150
AMBIENT TEMPERATURE ( oC)
PERCENT OF RATED VALUE
FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM
100
90
50
10
O
1
T
T
1
T
2
TIME
PERCENT OF PEAK VALUE
O
1
= Virtual Origin of Wave
T = Time From 10% to 90% of Peak
T
1
= Virtual Front time = 1.25 • t
T
2
= Virtual Time to Half Value (Impulse Duration)
Example: For an 8/20 µs Current Waveform:
8s = T
1
= Virtual Front Time
20 s = T
2
= Virtual Time to Half Value
Peak Pulse Current Test Waveform
01 = Virtual Origin of Wave
T = Time from 10% to 90% of Peak
T1 = Rise Time = 1.25 x T
T2 = Decay Time
Example - For an 8/20 µs Current Waveform:
8µs = T1 = Rise Time
20µs = T2 = Decay Time
Repetitive Surge Capability
FIGURE 8. SURGE CURRENT RATING CURVES FOR
V120MA SERIES - V430MA SERIES
100
50
20
10
5
2
1
0.5
0.2
0.1
SURGE CURRENT (A)
20 100 1,000 10,000
IMPULSE DURATION (μs)
2
10
102
103
1
104
105
106
INDEFINITE
DISC SIZE 3mm
V120MA1A - V430MA7B
V120MA1A/S - V430MA3A
FIGURE 7. SURGE CURRENT RATING CURVES FOR V18MA
SERIES - V100MA SERIES
50
20
10
5
2
1
0.5
0.2
0.1
2
10
102
103
DISC SIZE 3mm
V18MA1A - V100MA4B
1
104
105
INDEFINITE
106
20 100 1,000 10,000
IMPULSE DURATION (μs)
SURGE CURRENT (A)
V18MA - V100MA
NOTE: If pulse ratings are exceeded, a shift of VN(DC) (at specified current) of more than
+/-10% could result. This type of shift, which normally results in a decrease of VN(DC), may
result in the device not meeting the original published specifications, but it does not
prevent the device from continuing to function, and to provide ample protection.
Figure 1 Figure 2
Figure 3 Figure 4