CPC5610/CPC5611
rent. The photocurrent, a linear representation of the
receive signal, is amplified and converted to a differen-
tial voltage output on RX+ and RX-.
Figure 7. Differential and Single-ended Transmit
Path Connections to LITELINK
Host CODEC or
Transmit Circuit
LITELINK
Variations in gain are controlled to within ±1 dB by an
on-chip automatic gain control (AGC) circuit, which
sets the output of the photoamplifier to unity gain.
0.1uf
0.1uf
TX-
TXA1
TXA2
-
TX+
+
To accommodate single-supply operation, LITELINK
includes a small DC bias on the RX outputs of 1.0
Vdc. Most applications should AC couple the RX out-
puts as shown in Figure 6.
Host CODEC or
Transmit Circuit
LITELINK
LITELINK may be used for differential or single-ended
output as shown in Figure 6. Single-ended use will
produce 6 dB less signal output amplitude. Do not
0.1uf
0.1uf
TX-
TXA1
-
TX+
+
exceed 0 dBm into 600 Ω (2.2 V ) signal input.
P-P
Figure 6. Differential and Single-ended Receive
Path Connections to LITELINK
3.4 DC Characteristics
LITELINK
Host-side CODEC
or Voice Circuit
The CPC5610 and CPC5611 are designed for world-
wide application regarding DC characteristics, includ-
ing use under the requirements of TBR-21. The ZDC,
DCS1, and DCS2 pins control the VI slope character-
istics of LITELINK. Selecting appropriate resistor val-
0.1uF
0.1uF
RX+
RX+
RX-
RX-
ues for R
(R16) and R
(R15) in the provided
ZDC
DCS
application circuits assure compliance with DC
requirements.
0.1uF
RX+
RX
3.4.1 Resistive Termination Applications
LITELINK includes a telephone line current limit fea-
ture that is selectable by selecting the desired value
for R
(R16) using the following formula:
ZDC
3.3.2 Transmit Signal Path
Connect transmit signals from the host equipment to
the TX+ and TX- pins of LITELINK. Do not exceed a
1V
ICLAmps = ------------- + 0.011A
RZDC
signal level of 0 dBm in 600 Ω (or 2.2 V ). Differen-
P-P
Clare recommends using 8.2 Ω for R
in North
ZDC
tial transmit signals are converted to single-ended sig-
nals in LITELINK. The signal is coupled to the transmit
photodiode amplifier in a similar manner to the receive
path.
America and Japan, limiting telephone line current to
133 mA.
3.4.2 Reactive Termination Applications
The output of the photodiode amplifier is coupled to a
voltage-to-current converter via a transconductance
stage where the transmit signal modulates the tele-
phone line loop current. As in the receive path, gain is
set to unity automatically, limiting insertion loss to 0,
±1 dB.
TBR-21 sets the telephone line current limit at 60 mA.
To meet this requirement, set R
(R16) to 22.1 Ω.
ZDC
See Clare application note AN-146 Guidelines for Effec-
tive LITELINK Designs for information on FET heat sink-
ing in this application.
12
www.clare.com
Rev. 9.0