CPC5610/CPC5611

12

www.clare.com

Rev. 9.0

rent. The photocurrent, a linear representation of the

receive signal, is amplified and converted to a differen-

tial voltage output on RX+ and RX-.

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.

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.

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

exceed 0 dBm into 600

Ω (2.2 V

Figure 6. Differential and Single-ended Receive

Path Connections to LITELINK

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

signal level of 0 dBm in 600

Ω (or 2.2 V

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.

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.

Figure 7. Differential and Single-ended Transmit

Path Connections to LITELINK

3.4 DC Characteristics

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-

application circuits assure compliance with DC

requirements.

3.4.1 Resistive Termination Applications

LITELINK includes a telephone line current limit fea-

ture that is selectable by selecting the desired value

Clare recommends using 8.2

Ω for R

America and Japan, limiting telephone line current to

133 mA.

3.4.2 Reactive Termination Applications

TBR-21 sets the telephone line current limit at 60 mA.

See Clare application note AN-146 Guidelines for Effec-

tive LITELINK Designs for information on FET heat sink-

ing in this application.

RX+

RX-

RX+

RX+

RX

RX-

0.1uF

0.1uF

0.1uF

LITELINK

Host-side CODEC

or Voice Circuit

LITELINK

LITELINK

TXA1

TXA2

-

+

0.1uf

0.1uf

Host CODEC or

Transmit Circuit

Host CODEC or

Transmit Circuit

TX-

TX+

TXA1

-

+

0.1uf

0.1uf

TX-

TX+

1V

-------------

0.011A

+

=