SMT100
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. At this voltage (Vrm)
the current consumption of the SMT100 is negligible and will
not affect the protected system.
Resetting of the device to the non-conducting state is
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.
As with the avalanche T.V.S. device, if the SMT100 is subjected
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
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.
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.
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).
SELECTING A SMT100
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
I
BO
I
H
I
RM
V
RM
V
BR
V
BO
V
R
V
I
pp
I
COMPLIES WITH THE
FOLLOWING STANDARDS
PEAK SURGE
VOLTAGE
(V)
VOLTAGE
WAVEFORM
(
µS)
10/700
10/700
10/700
1.2/50
10/700
1.2/500
10/160
10/560
9/720
2/10
10/1000
2/10
0.5/700
CURRENT
WAVEFORM
(
µS)
5/310
5/310
5/310
1/20
5/310
8/20
10/160
10/560
5/320
2/10
10/1000
2/10
0.8/310
ADMISSIBLE
IPP
NECESSARY
RESISTOR
(A)
25
38
50
50
50
100
75
55
25
150
50
150
25
-
-
-
-
-
-
12.5
6.5
-
11.5
10
11.5
-
(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
1000
1500
2000
2000
level 3
level 4
1500
800
1000
2500
1000
5000
1000
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SMT100
ELECTRICAL CHARACTERISTICS (Tamb 25°C)
SYMBOL
V
RM
I
RM
V
R
V
BR
C
PARAMETER
Stand-off Voltage
Leakage Current at Stand-off Voltage
Continuous Reverse Voltage
Breakdown Voltage
Capacitance
SYMBOL
V
RO
I
H
I
BO
I
PP
I
R
PARAMETER
Breakover Voltage
Holding current
Breakover Current
Peak pulse Current
Continuous Reverse Current
THERMAL RESISTANCE
SYMBOL
R
TH
(J-I)
R
TH
(J-I)
PARAMETER
Junction to leads
Junction to ambient on printed circuit
(with standard footprint dimensions)
VALUE
20
100
UNIT
°
C/W
°
C/W
ABSOLUTE MAXIMUM RATINGS (Tamb 25°C)
SYMBOL
I
PP
PARAMETER
Peak pulse Current:
10/1000µS (open circuit voltage waveform 1kV 10/1000µS)
5/310µS (open circuit voltage waveform 4kV 10/700µS)
8/20µS (open circuit voltage waveform 4kV 1.2/50µS)
2/10µS (open circuit voltage waveform 2.5kV 2/10µS)
I
TSM
Non-repetitive surge peak on-state current
F = 50Hz
Non-repetitive surge peak on-state current
F = 50Hz
T
L
T
stg
T
j
Maximum lead temperature range
Storage temperature range
Maximum junction temperature
50Hz
60Hz
0.2s
2s
100
150
250
500
55
60
25
12
260
-55 to +150
150
A
A
A
A
A
A
A
A
VALUE
UNIT
°C
°C
°C
Type
Marking
I
RM
@ V
RM
MAX
(µA)
2
2
2
2
2
2
2
(V)
32
55
110
120
170
200
230
I
RM
@ V
R
MAX
(µA)
50
50
50
50
50
50
50
(V)
35
65
120
140
200
230
270
V
BO
@ I
BO
MAX
(V)
55
80
160
200
265
300
350
(mA)
800
800
800
800
800
800
800
I
H
MIN
(Note 1)
C
MAX
(pF)
180
160
140
140
130
120
120
Laser
SMT100-35
SMT100-65
SMT100-120
SMT100-140
SMT100-200
SMT100-230
SMT100-270
B035
B065
B120
B140
B200
B230
B270
(mA)
150
150
150
150
150
150
150
Note 1: Measured @ 1V bias, 1M
HZ.
All parameters are tested using a FET TEST model 3600.
TM
52
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