TISP4070L3BJ, TISP4350L3BJ
BIDIRECTIONAL THYRISTOR OVERVOLTAGE PROTECTORS
AUGUST 1999 — REVISED NOVEMBER 1999
To survive the Type A surges a fuse I2t value of 6.4 A2s is needed. Fuses, such as the 1.6 A 043601.6PR will
meet this criteria.
fuse values for UL 1950
Fuses for the UL 1950 power cross need to break the specified currents at 600 V a.c. - ordinary fuses will not
do! Fuse specification terms like short circuit capabilities to UL 1459 and UL 1950, 40 A, 7 A and 2.2 A at
600 V a.c. ensure that the 600 V breaking is met.
The requirement of Figure 3, box B, limits the fuse I2t to less than 100 A2s.
Box C, with its 1.3 A limit gives a flow division. Modems passing the FCC Part 68 Type A surge in a non-
operational mode, could use a 1 A fuse and satisfy the 1.3 A limit and move to box D. Modems operationally
passing the Type A surge will tend to use a 1.6 A fuse a fuse and move to box F. Fuses with ratings of 2 A and
above may not operate before the wiring simulator fails.
TISP4xxxL3BJ and UL 1950 power cross
The TISP4xxxL3BJ conducts current for periods greater than the power cross test times, Figure 2, so the
TISP4xxxL3BJ is not a major factor in UL 1950 compliance. The main design task for UL 1950 power cross
is about enclosure design and the selection of the other components that are subject to power cross. A UL
specified fuse together with a TISP4xxxL3BJ gives a simple design approach to meeting the power cross
requirements.
P R O D U C T
I N F O R M A T I O N
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