CH224ATF 데이터 시트보기 (PDF) - Cermetek Microelectronics
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CH224ATF Datasheet PDF : 13 Pages
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Cermetek Microelectronics, Inc.
CH224ATF Complete 2400 bps Modem Module
1. Current Limiting PSTN Protection Line
Device.
Current limiting is mandatory to meet UL safety
requirements. To maintain conveyed FCC Part
68 approval, the current limiting devices
identified as F1and F2 in dashed box #1 must
also survive FCC Part 68 surge tests. Use one
of the external component schemes defined
below in section 1A-1C to maintain compliance.
Reference Cermetek Application Note #126,
Supplemental PSTN Line Protection, for a more
detailed discussion.
A. A Raychem Polyfuse TR 600-150 (rated at 0.15
amps) is preferred because this device resets
automatically upon removal of the current flow.
Non-resettable devices such as Littlefuse, type
220003, or WICKMANN 19397-038 are also
acceptable.
B. Resistors (10Ω carbon film or 1/8 watt
minimum) may be used in Canada, as Canada
has no requirement that PSTN equipment be
operational after a type B surge test.
C. Although CSA CS-03 Part 1 (Canada) follows
the requirements of FCC Part 68 (USA),
Cermetek recommends contacting DOT
(Canada) and/or a certified independent lab to
verify compliance. For Canada, use either 10Ω
resistors (carbon film or SMD parts 1/8 watt
minimum) as described in paragraph B above,
or non-resettable fuses or resettable Polyfuses
as described in paragraph A above.
2. Over Voltage and Lightning Protection.
Surge Protection must be provided by
additional external components. This is
required to maintain conveyed FCC Part 68
approval. Refer to Cermetek Application Note
#126, Supplemental PSTN Line Protection, for
a more detailed discussion.
3. EMI/RFI Suppression.
No external EMI/RFI noise suppression circuitry
is required to maintain conveyed FCC Part 68
approval. However additional suppression, if
required for other reasons, may be added as
described below in Sections 3A–3B without
adversely effecting the FCC Part 68 approval.
A. To provide adequate EMI/RFI suppression, the
capacitor/inductor network contained in dashed
Box #3, Figure 1, should be located as close to
the RJ11 Jack as possible. Further, this
network should be provided with an excellent
ground path to the chassis.
B. Capacitors C1 and C2 should not exceed 0.005
µf. They must have a rating of 1.5 KV and
typically are .001 µf ± 20%. Recommended
devices for inductors L1 and L2 are Fair-Rite
2643666611 or 2943666661 or equivalent. For
UL applications, choose capacitors and
inductors that are UL 1950 listed. The actual
values of the components used may vary
depending on the end product design.
2001 Cermetek Microelectronics, Inc.
Page 12
Document No. 607-0005 Revision B1 (05/02)
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