CH1794A Cermetek Microelectronics, CH1794A Datasheet - Page 19

• Manufacturer Part Number: CH1794A
• Manufacturer: Cermetek Microelectronics

Specifications of CH1794A

• Lead Free Status / RoHS Status: Not Compliant

Cermetek Microelectronics, Inc.
Figure 6. PSTN Line Interface for all HS Modems. CH179XA-L/CH2056A-L and CH179XAR-L/CH2056AR-L
1. Current Limiting PSTN Protection Line Device.
2. Over Voltage and Lightning Protection.
3. Optional External Over Voltage and Lightning
2007 Cermetek Microelectronics, Inc.
Current limiting devices are mandatory to meet UL
safety standards. To maintain conveyed FCC Part
68 approval, the current limiting components
identified as F1 and F2 in dashed Box 1 must also
survive FCC Part 68 surge testing.
Cermetek Application Note #126, Supplemental
PSTN Line Protection, for more details. Refer to
Application Note # 130, Summary of Recommend
Suppliers, for a list of suppliers and associated part
numbers.
A resettable/repairable fuse (rated at 0.15 amps) is
preferred because it resets automatically upon
removal of the current flow. Non-resettable devices
are also acceptable.
(Canada) follows the requirements of FCC Part 68
(USA),
certified independent lab to verify compliance in the
specific application.
Surge Protection is provided by internal circuitry
contained within all HS modems. No additional
external components are required to maintain
conveyed FCC Part 68 approval for all HS modems
(excluding
CH179XAR-L/CH2056AR-L).
For
L/CH2056AR-L, the required surge protection
(identified as D1 in dashed Box 2) must be supplied
externally. The purchaser must include some form
of surge protection as described herein to maintain
conveyed FCC Part 68 approval.
Application Note # 130 for a list of suppliers.
Protection.
In most environments, the internal two terminal
surge suppressor (see dashed Box 3) is adequate.
CH179XA-L/CH2056A-L
models do NOT contain internal Surge Protection (Dashed Box 2). The purchaser MUST provide
external surge protection to maintain conveyed FCC Part 68 approval.
Cermetek
the
CH179XA-L/CH2056A-L
recommends
Although CS-03 Part 1
and
contacting
CH179XAR-
Refer to
Refer to
and
a
Page 19
4. EMI/RFI Suppression.
For severe environments, use an external three
terminal device with an earth ground as is shown in
dashed Box 3.
Suppression of emitted EMI/RFI is recommended
and is typically required to obtain FCC part 15 A
and/or B approval. EMI/RFI suppression circuitry is
also used to suppress reception of externally
generated EMI/RFI signals, such as strong radio
signals, should the CH1786A be located near a
source of such signals.
EMI/RFI noise suppression circuitry is required to
maintain
additional suppression may be added as described
below without adversely affecting FCC Part 68
approval.
A. To provide adequate EMI/RFI suppression, the
B. Capacitors C1 and C2 should not exceed
CH179XA/2056A High Speed Family of Ultra Small Modems
capacitor/inductor network contained in dashed
Box 5 should be located as close to the RJ-11C
Jack as possible. Further, this network should
be provided with an excellent ground path to the
chassis.
0.005µf. They must have a rating of 1.5KV and
typically are 0.001µf ± 20%. Inductors L1 and
L2 may be either individual inductors or a dual
inductor. Refer to Application Note #130 for a
complete list of recommended vendors and
associated part numbers. For UL applications,
choose capacitors and inductors that are UL
60950 Edition 3 listed. The actual values of the
components used may vary depending on the
end product design and the nature of the EMI/
RFI.
required.
Consult an FCC part 15 consultant if
conveyed
Document No. 607-0020 Revision B (01/07)
FCC
Although no external
Part
68
approval,