CPC5620 Datasheet, PDF (13/18 Pages) Clare, Inc. – LITELINK III Phone Line Interface IC (DAA)

3.5.2 Current Limited Applications
TBR-21 sets the telephone line current limit at 60 mA.
To meet this requirement, set R_ZDC (R16) to 22.1 Ω.
See Clare application note AN-146 Guidelines for Effec-
tive LITELINK Designs for information on FET heat sink-
ing in this application.
CPC5620/CPC5621
3.6 AC Characteristics
3.6.1 Resistive Termination Applications
y _{North American and Japanese telephone line AC ter-}
mination requirements are met with a resistive 600 Ω
r _{AC termination. Receive termination is applied to the}
LITELINK ZNT pin (pin 29) as a 301 Ω resistor, R_ZNT
a _(R10).
in ^{3.6.2 Reactive Termination Applications}
Many countries use a single-pole complex impedance
to model the telephone network transmission line
characteristic impedance as shown in the table below.
lim ^{Line Impedance Model}
TBR-21
Ra 750
Rb 270
Australian
820
220
re ^{C 150nF}
120 nF
P ^{Matching a complex impedance requires the use of}
complex network on ZNT as shown in the “Reactive
Termination Application Circuit” on page 8.
3.6.3 Mode Pin Usage
Assert the MODE pin low to introduce a 7 dB pad into
the transmit path and add 7 dB of gain to the receive
path. These changes compensate for the gain
changes made to the transmit and receive paths in
reactive termination implementations.
Insertion loss with MODE de-asserted and the resis-
tive termination application circuit is 0 dB. Insertion
loss with the reactive termination application circuit
and MODE asserted is also 0 dB.
Rev. 0.E
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