TMOV25SP385M Littelfuse Inc, TMOV25SP385M Datasheet - Page 210

• Manufacturer Part Number: TMOV25SP385M
• Description: TMOV VARISTOR PB FREE 25S
• Manufacturer: Littelfuse Inc
• Series: iTMOV®r

Specifications of TMOV25SP385M

• Varistor Voltage: 682V
• Current-surge: 20kA
• Number Of Circuits: 1
• Maximum Ac Volts: 385VAC
• Energy: 430J
• Package / Case: Disc 25mm 3-Lead
• Suppressor Type: Varistor
• Peak Surge Current @ 8/20µs: 20000A
• Varistor Case: 25mm DISC
• Clamping Voltage Vc Max: 1010V
• Peak Energy (10/1000us): 430J
• Voltage Rating Vdc: 682V
• Voltage Rating Vac: 385V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Maximum Dc Volts: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

For space applications, an extremely important property
of a protection device is its response to imposed radiation
effects.
Electron Irradiation
Neutron Effects
High Reliability Varistors
Radiation Hardness
A Littelfuse MOV and a Silicon transient suppression diode
were exposed to electron irradiation. The V-I curves, before
and after test, are shown below.
It is apparent that the Littelfuse MOV was virtually
unaffected, even at the extremely high dose of 108 rads,
while the Silicon transient suppression diode showed a
dramatic increase in leakage current.
A second MOV-Zener comparison was made in response
to neutron fluence. The selected devices were equal in
area.
Figure 2 shows the clamping voltage response of the MOV
and the Zener to neutron irradiation to as high as 1015 N/
cm
the Zener, the MOV is unaltered. At highercurrents where
the MOV’s clamping voltage is again unchanged, the Zener
device clamping voltage increases by as much as 36%.
V
300
200
100
2
80
60
50
40
30
20
10
FIGURE 2. V-I CHARACTERISTIC RESPONSE TO NEUTRON
200
100
. It is apparent that in contrast to the large change in
FIGURE 1. RADIATION SENSITIVITY OF LITTELFUSE V130LA1
80
60
40
20
10
VARISTOR V130A2
10
8
INITIAL AT 10
10
IRRADIATION FOR MOV AND ZENER DIODE
DEVICES
AND SILICON TRANSIENT SUPPRESSION DIODE
10
10
15
6
8
10
AMPERES
CURRENT (A)
1.5K 200 INITIAL
7
10
10
4
6
1.5K 200
AT 10
PRE TEST
10
18MeV ELECTRONS
8
RADS,
15
10
LITTELFUSE MOV
SILICON
TRANSIENT
SUPPRESSION
DIODE
5
10
10
4
2
10
3
High Reliability Varistors
Revision: November 5, 2009
Varistor Products
206
Counterclockwise rotation of the V-I characteristics is
observed in Silicon devices at high neutron irradiation
levels; in other words, increasing leakage at low current
levels and increasing clamping voltage at higher current
levels.
The solid and open circles for a given fluence represent the
high and low breakdown currents for the sample of devices
tested. Note that there is a marked decrease in current (or
energy) handling capability with increased neutron fluence.
Failure threshold of Silicon semiconductor junctions is
further reduced when high or rapidly increasing currents
are applied. Junctions develop hot spots, which enlarge
until a short occurs if current is not limited or quickly
removed.
The characteristic voltage current relationship of a P– N
Junction is shown below.
At low reverse voltage, the device will conduct very little
current (the saturation current). At higher reverse voltage
VBO (breakdown voltage),the current increases rapidly as
the electrons are either pulled by the electric field (Zener
effect) or knocked out by other electrons (avalanching). A
further increase in voltage causes the device to exhibit a
negative resistance characteristic leading to secondary
breakdown.
This manifests itself through the formation of hotspots,
and irreversible damage occurs. This failure threshold
decreases under neutron irradiation for Zeners, but not for
Z
Gamma Radiation
Radiation damage studies were performed on type
V130LA2 varistors. Emission spectra and V-I characteristics
were collected before and after irradiation with 106 rads
Co60 gamma radiation. Both show no change, within
experimental error, after irradiation.
N
O Varistors.
REDUCTION IN
FAILURE STRESSHOLD
BY RADIAL
FIGURE 3. V-I CHARACTERISTIC OF PN-JUNCTION
BREAKDOWN
VOLTAGE
BREAKDOWN
SECONDARY
Please refer to www.littelfuse.com/series/za hirel.html or /db hirel.html
SATURATION
CURRENT
REVERSE
BIAS
Specifications are subject to change without notice.
I
FORWARD
BIAS
for current information.
©2009 Littelfuse, Inc.
V