V18MA1A_09 Datasheet, PDF (3/5 Pages) Littelfuse – Axial Lead / Application Specific Varistors

Varistor Products
Axial Lead / Application Specific Varistors > MA Series
Power Dissipation Ratings
Peak Pulse Current Test Waveform
100
90
80
70
60
50
40
30
20
10
0
-55 50 60 70 80 90 100 110 120 130 140 150
Figure 1
AMBIENT TEMPERATURE ( ^oC)
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.
100
90
50
10
O₁
Figure 2
T
T₁
T₂
TIME
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
V18MA - V100MA
50 ₁
2
20
10
10 ₁₀₂
5 ₁₀₃
2 ¹⁰⁴
DISC SIZE 3mm
V18MA1A - V100MA4B
10
5
10⁶
1
0.5
INDEFINITE
0.2
0.1
20
Figure 3
100
1,000
IMPULSE DURATION (μs)
10,000
V120MA1A/S - V430MA3A
100
50 ^{2 1}
10
20
10 ¹⁰²
5
DISC SIZE 3mm
V120MA1A - V430MA7B
10³
10⁴
10⁵
10⁶
2
1
0.5
0.2
0.1
20
Figure 4
INDEFINITE
100
1,000
IMPULSE DURATION (μs)
10,000
NOTE: If pulse ratings are exceeded, a shift of V_N(DC) (at specified current) of more than
+/-10% could result. This type of shift, which normally results in a decrease of V_N(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.
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/ma.html for current information.
185
Revision: January 9, 2009
MA Varistor Series