© 2015 Littelfuse, Inc.

Specifications are subject to change without notice.

Revised: 11/04/15

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)

FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM

100

90

50

10

O1

T

T1

T2

TIME

O1 = Virtual Origin of Wave

T = Time From 10% to 90% of Peak

T1 = Virtual Front time = 1.25 • t

T2 = Virtual Time to Half Value (Impulse Duration)

Example: For an 8/20 µsCurrent Waveform:

8s = T1 = Virtual Front Time

20 s = T2 = Virtual Time to Half Value

Peak Pulse Current Test Waveform

0

1 = Virtual Origin of Wave

T = Time from 10% to 90% of Peak

T

1 = Rise Time = 1.25 x T

T

2 = Decay Time

Example - For an 8/20

µs Current Waveform:

8µs = T

1 = Rise Time

20µs = T

2 = 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

20

100

1,000

10,000

IMPULSE DURATION (s)

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 (s)

V18MA - V100MA

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.

Figure 1

Figure 2

Figure 3

Figure 4