SMT100-120 Littelfuse, Inc., SMT100-120 Datasheet

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SMT100-120

Manufacturer Part Number
SMT100-120
Description
Manufacturer
Littelfuse, Inc.
Datasheet
The electrical characteristics of a SMT100 device are similar to
that of a self-gated Triac, but the SMT100 is a two terminal
device with no gate. The gate function is achieved by an
internal current controlled mechanism.
Like the T.V.S. diodes, the SMT100 has a standoff voltage
(Vrm) which should be equal to or greater than the operating
voltage of the system to be protected. At this voltage (Vrm)
the current consumption of the SMT100 is negligible and will
not affect the protected system.
When a transient occurs, the voltage across the SMT100 will
increase until the breakdown voltage (Vbr) is reached. At this
point the device will operate in a similar way to a T.V.S.
device and is in avalanche mode.
The voltage of the transient will now be limited and will only
increase by a few volts as the device diverts more current. As
this transient current rises, a level of current through the
1. When selecting a SMT100 device, it is important
that the Vrm of the device is equal to or greater than
the the operating voltage of the system.
2. The minimum Holding Current (Ih) must be greater
than the current the system is capable of delivering
otherwise the device will remain conducting
following a transient condition.
ELECTRICAL CHARACTERISTICS
SELECTING A SMT100
COMPLIES WITH THE
FOLLOWING STANDARDS
(CCITT) ITU-K20
(CCITT) ITU-K17
VDE0433
VDE0878
IEC-1000-4-5
FCC Part 68, lightning surge
type A
FCC Part 68, lightning surge
type B
Bellcore TR-NWT-001089
first level
Bellcore TR-NWT-001089
second level
CNET I31-24
PEAK SURGE
VOLTAGE
level 3
level 4
1500
1000
1000
1500
2000
2000
2500
1000
5000
1000
800
(V)
WAVEFORM
VOLTAGE
10/1000
1.2/500
0.5/700
10/700
10/700
10/700
10/700
10/160
10/560
1.2/50
9/720
2/10
2/10
w w w . l i t t e l f u s e . c o m
(
µS)
WAVEFORM
CURRENT
device is reached (Ibo) which causes the device to switch to a
fully conductive state such that the voltage across the device
is now only a few volts (Vt). The voltage at which the device
switched from the avalanche mode to the fully conductive
state (Vt) is known as the Breakover voltage (Vbo). When the
device is in the Vt state, high currents can be diverted
without damage to the SMT100 due to the low voltage across
the device, since the limiting factor in such devices is
dissipated power (V x I).
Resetting of the device to the non-conducting state is
controlled by the current flowing through the device. When
the current falls below a certain value, known as the Holding
Current (Ih), the device resets automatically.
As with the avalanche T.V.S. device, if the SMT100 is subjected
to a surge current which is beyond its maximum rating, then
the device will fail in short circuit mode, ensuring that the
equipment is ultimately protected.
10/1000
0.8/310
10/160
10/560
V-I Graph illustrating symbols
and terms for the SMT100
surge protection device
5/310
5/310
5/310
5/310
5/320
1/20
8/20
2/10
2/10
(
µS)
ADMISSIBLE IPP
100
150
150
(A)
25
38
50
50
50
75
55
25
50
25
NECESSARY
RESISTOR
12.5
11.5
11.5
6.5
10
-
-
-
-
-
-
-
-
I
I
I
I
pp
BO
H
RM
I
SMT100
V
RM
V
R
V
BR
V
BO
V
51

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SMT100-120 Summary of contents

Page 1

... ELECTRICAL CHARACTERISTICS The electrical characteristics of a SMT100 device are similar to that of a self-gated Triac, but the SMT100 is a two terminal device with no gate. The gate function is achieved by an internal current controlled mechanism. Like the T.V.S. diodes, the SMT100 has a standoff voltage (Vrm) which should be equal to or greater than the operating voltage of the system to be protected ...

Page 2

... Maximum lead temperature range L T Storage temperature range stg T Maximum junction temperature j Marking Type Laser B035 SMT100-35 B065 SMT100-65 B120 SMT100-120 SMT100-140 B140 SMT100-200 B200 SMT100-230 B230 B270 SMT100-270 Note 1: Measured @ 1V bias, 1M HZ. All parameters are tested using a FET TEST 52 SYMBOL V I ...

Page 3

... SMT100 53 ...

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