© 2013 Littelfuse, Inc.
195
Revised: May 8, 2013
Varistor Products
RA Varistor Series
Low Profile / Application Specific Varistors > RA Series
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/ra.html for current information.
RA Series
Part
Number
Brand
Maximum Rating (125°C) Specifications (25°C)
Continuous Transient
Varistor Voltage at 1mA
DC Test Current
Max Clamping
Volt V
C
at 2.0A
(8/20μs)
Typical
Capacitance
V
RMS
V
DC
Energy
(10/1000μs)
Peak
Current
(8/20μs)
V
M(AC)
V
M(DC)
W
TM
I
TM
Min V
N(DC)
Max V
C
I
p
f = 1MHz
(mm) (V) (V) (J) (A) (V) (V) (V) (V) (A) (pF)
† RA22 Series
V24RA22 24R22 14
18
(Note 3)
100.0
(Note 2)
2000 19.2
24
(Note 4)
26 43 20 18000
V36RA22 36R22 23 31
160.0
(Note 2)
2000 32
36
(Note 4)
40 63 20 12000
† V200RA22 200R22 130 175 70.0 6500 184 200 228 340 100 1900
† V240RA22 240R22 150 200 80.0 6500 212 240 268 395 100 1600
† V270RA22 270R22 175 225 90.0 6500 247 270 303 455 100 1400
† V390RA22 390R22 250 330 130.0 6500 354 390 429 650 100 1000
† V430RA22 430R22 275 369 140.0 6500 389 430 473 710 100 900
RA Series Ratings & Specifications
NOTES:
1. Average power dissipation of transients not to exceed 0.25W for RA8 Series, 0.60W for RA16 Series, or 1.0W for RA22 Series.
2. Energy ratings for impulse duration of 30ms minimum to one half of peak current value.
3. Also rated to withstand 24V for 5 minutes.
4. 10mA DC Test Current.
† Under UL File No. E320116 as a recognized component. CSA approved File No. LR91788.
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 aver-
age power dissipation.
Power Dissipation Ratings
100
90
50
10
1
T
T
1
T
2
TIME
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
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 RATED VALUE
Figure 1
Figure 2
(2 Seiten)
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