Surface Mount Varistors
Transient Voltage Surge Suppressor
Pb
RoHS
CH Varistor Series
Power Dissipation Ratings
100
90
80
70
60
50
40
Continuous power dissipation capability is not an applicable design
requirement for a suppressor, unless transients occur in rapid succession.
Under this condition, 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 tempera-
tures as shown in Figure 1. 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.
30
20
10
0
-55
50
60
70
80
90 100 110 120 130 140 150
o
AMBIENT TEMPERATURE ( C)
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE
100
90
3
O
= Virtual Origin of Wave
1
T = Time From 10% to 90% of Peak
T
T
= Virtual Front time = 1.25 • t
= Virtual Time to Half Value (Impulse Duration)
1
2
50
Example: For an 8/20µs Current Waveform:
8µs = T = Virtual Front Time
1
20µs = T = Virtual Time to Half Value
2
10
O
T
TIME
1
T
1
T
2
FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM
Transient V-I Characteristics Curves
4,000
3,000
500
400
MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 5 x 8mm
MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 5 x 8mm
100 TO 430V
RATING
300
N(DC)
= -55 C TO 125 C
o
o
T
22 TO 56V
o
RATING
o
2,000
A
N(DC)
= -55 C TO 125 C
200
T
V430CH8
V390CH8
V360CH8
A
1,000
900
800
700
600
500
400
V240CH8
V220CH8
V200CH8
100
90
80
70
60
50
40
V68CH8
V56CH8
V47CH8
V39CH8
V33CH8
V27CH8
V22CH8
300
200
30
20
V180CH8
V150CH8
V120CH8
100
10
10
-3
-2
10
-1
10
0
1
2
3
4
10
10
10
10
10
-3
-2
10
-1
10
0
1
2
3
10
10
10
10
10
PEAK AMPERES (A)
FIGURE 4. CLAMPINGVOLTAGE FOR V120CH8 - V430CH8
197
PEAK AMPERES (A)
FIGURE 3. CLAMPING VOLTAGE FOR V22CH8 - V68CH8
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