LITTELFUSE SMT100-120, SMT100-140, SMT100-200, SMT100-230, SMT100-270 Datasheet
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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
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.
ELECTRICAL CHARACTERISTICS
SELECTING A SMT100
COMPLIES WITH THE PEAK SURGE VOLTAGE CURRENT ADMISSIBLE IPP NECESSARY
FOLLOWING STANDARDS VOLTAGE WAVEFORM WAVEFORM RESISTOR
(V) (
µS) (µS) (A)
(CCITT) ITU-K20 1000 10/700 5/310 25 -
(CCITT) ITU-K17 1500 10/700 5/310 38 -
-
VDE0433 2000 10/700 5/310 50
VDE0878 2000 1.2/50 1/20 50 -
IEC-1000-4-5 10/700 5/310 50 -
level 4 1.2/500 8/20 100 -
FCC Part 68, lightning surge 1500 10/160 10/160 75 12.5
type A 800 10/560 10/560 55 6.5
FCC Part 68, lightning surge 1000 9/720 5/320 25 -
type B
Bellcore TR-NWT-001089 2500 2/10 2/10 150 11.5
first level 1000 10/1000 10/1000 50 10
Bellcore TR-NWT-001089 5000 2/10 2/10 150 11.5
second level
CNET I31-24 1000 0.5/700 0.8/310 25 -
level 3
V
R
V
BR
V
RM
V
BO
I
RM
I
BO
I
H
I
pp
I
V
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.
V-I Graph illustrating symbols
and terms for the SMT100
surge protection device
SMT100
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SMT100
Note 1: Measured @ 1V bias, 1MHZ.
All parameters are tested using a FET TEST
TM
model 3600.
ELECTRICAL CHARACTERISTICS (Tamb 25°C)
ABSOLUTE MAXIMUM RATINGS (Tamb 25°C)
THERMAL RESISTANCE
SYMBOL PARAMETER SYMBOL PARAMETER
V
RM
Stand-off Voltage V
RO
Breakover Voltage
I
RM
Leakage Current at Stand-off Voltage I
H
Holding current
V
R
Continuous Reverse Voltage I
BO
Breakover Current
V
BR
Breakdown Voltage I
PP
Peak pulse Current
C Capacitance I
R
Continuous Reverse Current
SYMBOL PARAMETER VALUE UNIT
R
TH
(J-I) Junction to leads 20 °C/W
R
TH
(J-I) Junction to ambient on printed circuit 100 °C/W
(with standard footprint dimensions)
SYMBOL PARAMETER VALUE UNIT
I
PP
Peak pulse Current:
10/1000µS (open circuit voltage waveform 1kV 10/1000µS) 100 A
5/310µS (open circuit voltage waveform 4kV 10/700µS) 150 A
8/20µS (open circuit voltage waveform 4kV 1.2/50µS) 250 A
2/10µS (open circuit voltage waveform 2.5kV 2/10µS) 500 A
I
TSM
Non-repetitive surge peak on-state current 50Hz 55 A
F = 50Hz 60Hz 60 A
Non-repetitive surge peak on-state current 0.2s 25 A
F = 50Hz 2s 12 A
T
L
Maximum lead temperature range 260 °C
T
stg
Storage temperature range -55 to +150 °C
T
j
Maximum junction temperature 150 °C
Type
SMT100-35
SMT100-65
SMT100-120
SMT100-140
SMT100-200
SMT100-230
SMT100-270
Marking
Laser
B035
B065
B120
B140
B200
B230
B270
IRM @ VRM
MAX
(µA) (V)
IRM @ VR
MAX
(µA) (V)
35
65
120
140
200
230
270
50
50
50
50
50
50
50
800
800
800
800
800
800
800
55
80
160
200
265
300
350
32
55
110
120
170
200
230
2
2
2
2
2
2
2
VBO @ IBO
MAX
(V) (mA)
IH
MIN
(Note 1)
(mA)
150
150
150
150
150
150
150
C
MAX
(pF)
180
160
140
140
130
120
120
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