
NOVEMBER 2001 - REVISED FEBRUARY 2005
Specifications are subject to change without notice.
Customers should verify actual device performance in their specific applications.
APPLICATIONS INFORMATION
TISP43xxMMAJ/BJ Overvoltage Protector Series
FCC Part 68, ACTA, TIA and EIA
Fuse Values for TIA/EIA-IS-968 (FCC Part 68)
Fuses must not operate on the Type B surge. To survive a 37.5 A Type B surge, the fuse needs to have a melting I
2
t of greater than 0.7 A
2
s.
To survive the Type A surges a fuse melting I
2
t value of greater than 10 A
2
s for 10/160 and 8 A
2
s for 10/560 is needed. By using a fuse which
does not operate on Type B surges (I
2
t > 0.7 A
2
s) and does operate on Type A surges (I
2
t < 8 A
2
s) a non-operational pass can be achieved for
Type A testing.
From 2001, the registrations for FCC equipment changed from the FCC to ACTA, Administrative Council for Terminal Attachments. For this
function, ACTA needed to adopt a US National standard specifying terminal equipment requirements. The TIA, Telecommunications
Industry Association, in conjunction with the EIA, Electronic Industries Alliance, created TIA/EIA-IS-968 for this purpose. The first issue of
TIA/EIA-IS-968 is essentially a renumbered version of the FCC Part 68 requirement. Clause and figure changes are shown in the table.
Item
FCC Part 68
Clause 68.302 (b)
Clause 68.302 (c)
Fig. 68.302 (a)
Fig. 68.302 (b)
Fig. 68.302 (c)
TIA/EIA-IS-968
Clause 4.2.2
Clause 4.2.3
Figure 4.1
Figure 4.2
Figure 4.3
Telephone Line Surge – Type A
Telephone Line Surge – Type B
Simplified Surge Generator
Open Circuit voltage Wave shape
Short Circuit Current Wave shape
TIA/EIA-IS-968 (FCC Part 68) Impulse Testing
To verify the withstand capability and safety of the equipment, standards require that the equipment is tested with various impulse wave forms.
The table below shows values for the TIA/EIA-IS-968 and ITU-T recommendation K.21.
Standard
Test
Condition
V
Longitudinal
Metallic
Longitudinal
Metallic
Peak
Voltage
V
1500
800
1500
1000
1500
4000
1500
6000
Voltage
Wave Form
μ
s
10/160
10/560
9/720
9/720
Peak
Current
A
200
100
37.5
25
37.5
100
37.5
125
Current
Wave Form
μ
s
10/160
10/560
5/320
5/320
Fictive
Impedance
7.5
8
40
40
TISP43xxMM
Rating
A
75
55
65
65
Series
Resistance
TIA/EIA-IS-968
(FCC Part 68)
2 x 13
7
0
0
0
6.6
0
6.2
ITU-T K.21
Basic Level
ITU-T K.21
Enhanced Level
TIA/EIA-IS-968 terminology for the wave forms produced by the ITU-T recommendation K.21 10/700 impulse generator
Values assume the TISP43xxMM is connected inter-conductor and a 400 V primary is used
Transverse
10/700
5/310
40
65
Transverse
10/700
5/310
40
65
If the impulse generator current exceeds the protector’s current rating then a series resistance can be used to reduce the current to the
protector’s rated value to prevent possible failure. For the new edition of ITU-T recommendation K.21 (2000) some series resistance might
be needed to pass the impulse coordination test. The value for a 400 V primary protector is given in the table.
The required value of device survival series resistance for a given waveform is given by the following calculations. First, the minimum total
circuit impedance is found by dividing the impulse generator’s peak voltage by the protector’s rated current. The impulse generator’s fictive
impedance (generator’s peak voltage divided by peak short circuit current) is then subtracted from the minimum total circuit impedance to
give the required value of series resistance.
For the TIA/EIA-IS-968 10/560 waveform the following values result. The minimum total circuit impedance is 800/55 = 15
and the
generator’s fictive impedance is 800/100 = 8
. For an inter-conductor connected TISP43xxMM, this gives a minimum series resistance value
of 15 - 8 = 7
. The 10/160 waveform only needs to be considered if the TISP43xxMM is connected from the conductor to ground. In this
case the conductor series resistance is 12.5
per conductor.