SI2400 Datasheet, PDF (68/76 Pages) List of Unclassifed Manufacturers – V.22BIS ISOMODEM™ WITH INTEGRATED GLOBAL DAA

Si2400
APPENDIX C—UL1950 3RD EDITION
Designs using the Si2400 pass all overcurrent and over-
voltage tests for UL1950 3rd Edition compliance with a
couple of considerations.
Figure 18 shows the designs that can pass the UL1950
overvoltage tests, as well as electromagnetic
emissions. The top schematic of Figure 18 shows the
configuration in which the ferrite beads (FB1, FB2) are
on the unprotected side of the sidactor (RV1). For this
configuration, the current rating of the ferrite beads
must be 6 A.
The bottom schematic of Figure 18 shows the
configuration in which the ferrite beads (FB1, FB2) are
C24
on the protected side of the sidactor (RV1). For this
design, the ferrite beads can be rated at 200 mA.
In a cost-optimized design, it is important to remember
that compliance to UL1950 does not always require
overvoltage tests. It is best to plan ahead and know
which overvoltage tests will apply to your system.
System-level elements in the construction, such as fire
enclosure and spacing requirements, need to be
considered during the design stages. Consult with your
Professional Testing Agency during the design of the
product to determine which tests apply to your system.
75 Ω @ 100 MHz, 6 A
1.25 A
Fuse/PTC
FB1
TIP
RV1
75 Ω @ 100 MHz, 6 A
C25
FB2
Note: In this configuration, C24 and C25 are
used for emissions testing.
RING
1000 Ω @ 100 MHz, 200 mA
C24
FB1
1000 Ω @ 100 MHz, 200 mA ^RV1
FB2
C25
1.25 A
Fuse/PTC
TIP
RING
Figure 18. Circuits that Pass all UL1950 Overvoltage Tests
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Rev. 0.95