CPC5610/CPC5611
The information provided in this document is intended
to inform the equipment designer but it is not sufficient
to assure proper system design or regulatory compli-
ance. Since it is the equipment manufacturer's respon-
sibility to have their equipment properly designed to
conform to all relevant regulations, designers using
LITELINK are advised to carefully verify that their end-
product design complies with all applicable safety,
EMC, and other relevant standards and regulations.
Semiconductor components are not rated to withstand
electrical overstress or electro-static discharges result-
ing from inadequate protection measures at the board
or system level.
3.5 AC Characteristics
3.5.1 Resistive Termination Applications
North American and Japanese telephone line AC ter-
mination requirements are met with a resistive 600 Ω
AC termination. Receive termination is applied to the
LITELINK ZNT pin (pin 29) as a 301 Ω resistor, R
ZNT
(R10). A 150 Ω resistor, R18 (R ), applied to the
ZTX
LITELINK ZTX pin (pin 30) sets the correct transmit
gain and impedance.
3.5.2 Reactive Termination Applications
Many areas use a single-pole complex impedance to
model the telephone network transmission line char-
acteristic impedance as shown in the table below.
Line Impedance Model
TBR-21
Australian
Ra
Rb
750
270
820
220
C
150 nF
120 nF
Matching a complex impedance requires the use of
complex networks on ZNT and ZTX. In order to
accommodate high power levels, it is necessary to
modify the transmit and receive gain characteristics of
your LITELINK implementation. The complex network
on the ZTX pin increases transmit gain by 7 dB. A 7
dB pad may be inserted before the TX+ and TX- pins
to provide overall unity gain. Similarly, with a complex
network, the ratio of R12 (R
) and R13 (R
) must
NTF
NTS
be modified from 1:1 to 1:.287, which introduces a 7
dB loss in the receive path from tip and ring to ZNT.
4. Regulatory Information
LITELINK can be used to build products that comply
with the requirements of TIA/EIA/IS-968 (formerly
FCC part 68), FCC part 15B, TBR-21, EN60950,
UL1950, EN55022B, IEC950/IEC60950, CISPR22B,
EN55024, and many other standards. LITELINK com-
plies with the requirements of UL1577. LITELINK pro-
vides supplementary isolation. Metallic surge
requirements are met through the inclusion of a Sidac-
tor in the application circuit. Longitudinal surge protec-
tion is provided by LITELINK’s optical-across-the-
barrier technology and the use of high-voltage compo-
nents in the application circuit as needed.
Rev. 9.0
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