CH1788 Cermetek Microelectronics, CH1788 Datasheet - Page 13

• Manufacturer Part Number: CH1788
• Manufacturer: Cermetek Microelectronics

Specifications of CH1788

• Lead Free Status / RoHS Status: Supplier Unconfirmed

Cermetek Microelectronics, Inc.
Figure 3.
1. Current Limiting PSTN Protection Line
2. PSTN Current Limiting Resistors.
3. Over Voltage and Lightning Protection.
2006 Cermetek Microelectronics, Inc.
Device.
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 be
included. Refer to Cermetek Application Note #
126, Supplemental PSTN Line Protection, for
more details. Refer to Cermetek Application Note
# 130, Summary of Recommended Suppliers, for
a list of suppliers and manufactures part numbers.
A resettable/repairable fuse (rated at 0.15 amps)
is preferred because it resets automatically upon
removal of the current flow.
devices are also acceptable. 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.
Low value (10Ω) 1/2 watt resistors may be
required (identified as R1 and R2 in dashed Box
2),
environment, to enhance performance by reducing
susceptibility to PSTN current surges that may
occur before the OVERVOLTAGE PROTECTION
device (identified as D1 in dashed Box 3)
becomes fully activated.
Refer to Cermetek Application Note # 130,
Summary of Recommended Supplies, for a list of
suppliers.
To maintain conveyed FCC Part 68 approval for all
CH1788 Products, the required surge protection
must be supplied externally. It is required that a
Sidactor or equivalent fast acting device be used.
DO NOT USE AN MOV OR A TRANSORB.
depending
PSTN Line Interface for all CH1788 Products.
on
end
product
Non-resettable
application
Page 13
4. EMI/RFI Suppression.
The Sidactor or equivalent should be nominally
rated at between 270-300 Volts.
environments, 2 terminal surge suppressors are
adequate.
external 3 terminal device with an earth ground as
is shown.
EMI/RFI suppression is recommended. This is for
obtaining FCC part 15 A and/or B. It is also used
to suppress external EMI / RFI signals that can
affect modem operation, such as strong radio
signals, should the modem be near a source of
such signals.
suppression circuitry is required to maintain
conveyed FCC Part 68 approval.
suppression may be added as described below
without adversely affecting FCC Part 68 approval.
A. To provide adequate EMI/RFI suppression,
B. Capacitors C1 and C2 should not exceed
the capacitor/inductor network contained in
dashed Box 4 should be located as close to
the RJ-11C Jack as possible.
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.
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 and the nature of the
EMI/ RFI. Consult an FCC part 15 consultant
if required.
CH1788 Surface Mount PLCC 2400bps Modem
For severe environments, use an
Document No. 607-0018 Revision A6 (01/06)
No external EMI/RFI noise
Further, this
Additional
In most
For UL