V240CH8 查看數據表（PDF） - Littelfuse, Inc
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V240CH8 Datasheet PDF : 5 Pages
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Surface Mount Varistors
Transient Voltage Surge Suppressor
RoHS Pb CH Varistor Series
Power Dissipation Ratings
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.
100
90
80
70
60
50
40
30
20
10
0
-55 50 60 70 80 90 100 110 120 130 140 150
AMBIENT TEMPERATURE ( oC)
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE
100
3
90
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)
50
Example: For an 8/20µs Current Waveform:
8µs = T1 = Virtual Front Time
20µs = T2 = Virtual Time to Half Value
10
O1
T
T1
T2
TIME
FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM
Transient V-I Characteristics Curves
500
400 MAXIMUM CLAMPING VOLTAGE
300 MODEL SIZE 5 x 8mm
22 TO 56VN(DC) RATING
200 TA = -55oC TO 125oC
100
90
80
V68CH8
70 V56CH8
60 V47CH8
50 V39CH8
40 V33CH8
V27CH8
30 V22CH8
20
4,000
3,000
2,000
1,000
900
800
700
600
500
400
MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 5 x 8mm
1TA00=T-O554o3C0VTON(D12C5) oRCATING
V240CH8
V220CH8
V200CH8
V430CH8
V390CH8
V360CH8
300
200
V180CH8
V150CH8
V120CH8
10
10-3
10-2
10-1
100
101
PEAK AMPERES (A)
102
103
FIGURE 3. CLAMPING VOLTAGE FOR V22CH8 - V68CH8
100
10-3
10-2 10-1
100
101
102
PEAK AMPERES (A)
103 104
FIGURE 4. CLAMPINGVOLTAGE FOR V120CH8 - V430CH8
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