Varistor products, Surface mount varistors > sm7 series, Sm7 series – Littelfuse SM7 Varistor Series User Manual
Page 3: Pulse rating curves, V-i limit curves
© 2013 Littelfuse, Inc.
77
Revised: May 8, 2013
Varistor Products
SM7 Series Varistor
Surface Mount Varistors > SM7 Series
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/sm7.html for current information.
SM7 Series
For applications exceeding 85ºC ambient temperature, the peak
surge current and energy ratings must be reduced as shown below
Peak Pulse Current Test Waveform for Clamping Voltage
Peak Current, Energy and Power Derating Curve
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
PERCEN
T OF PEAK
V
ALUE
T
est
0
50
100
TIM E
t
1
t
t
O
1
Pulse Rating Curves
1
10
100
1000
10000
10
100
1000
10000
Impulse Duration (μs)
S
u
rg
e
C
u
rre
n
t (A
)
1
2
10
10
2
10
3
10
4
10
5
10
6
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.
V-I Limit Curves
0
500
1000
1500
2000
0.001
0.01
0.1
1
10
100
1000
Current(A)
Voltage(V)
V510SM7
V480SM7
V460SM7
V420SM7
V385SM7
V320SM7
V300SM7
V250SM7
V230SM7
V210SM7
V190SM7
V175SM7
V150SM7
V140SM7
V130SM7
V115SM7
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 (
o
C)
PERCENT OF R
A
TED V
ALUE