CA16B2CNN datasheet(13/30 Pages) AGERE

13 / 30 page

Agere Systems Inc.

Advance Data Sheet

CA16-Type 2.5 Gbits/s DWDM Transponder with

March 2001

16-Channel 155 Mbits/s Multiplexer/Demultiplexer

Functional Description (continued)

Loopback Modes

The CA16-type transponder is capable of operating in

either of two loopback modes: diagnostic loopback or

line loopback.

Line Loopback

When LLOOP is pulled low, the received serial data

stream and recovered 2488.32 MHz serial clock from

the optical receiver are connected directly to the serial

data and clock inputs of the optical transmitter. This

establishes a receive-to-transmit loopback at the serial

line rate.

Diagnostic Loopback

When DLOOP is pulled low, a loopback path is estab-

lished from the transmitter to the receiver. In this mode,

the serial data from the parallel-to-serial converter and

the transmit serial clock is looped back to the serial-to-

parallel converter and the frame and byte detect cir-

cuitry, respectively.

Transponder Interfacing

The TxD[0:15]P/N, TxREFCLKP/N, and PICLKP/N

inputs and the RxQ[0:15]P/N, POCLKP/N, and PCLKP/

N outputs are high-speed (155 Mbits/s),LVPECL differ-

ential data and clock signals.To maintain optimum sig-

nal fidelity, these inputs and outputs must be

connected to their terminating devices via 50 ¾ con-

trolled-impedance transmission lines. The transmitter

inputs (TxD[0:15]P/N, TxREFCLKP/N, and PICLKP/N)

must be terminated as close as possible to the CA16

transponder connector with a Thevenin equivalent

impedance equal to 50

Ω terminated to Vcc – 2 V. The

receiver outputs (RxQ[0:15]P/N, POCLKP/N, and

PCLKP/N) must be terminated as close as possible to

the device (IC) that these signals interface to with a

Thevenin equivalent impedance equal to 50

Ω termi-

nated to Vcc – 2 V.

Figure 3, below, shows one example of the proper ter-

minations. Other methods may be used, provided they

meet the requirements stated above.

1-1054(F)

Figure 3. Transponder Interfacing

TxD[0:15]P

130

Ω

130

Ω

3.3 V

130

Ω

130

Ω

3.3 V

SONET/SDH

RxLINE

TxLINE

Ω IMPEDANCE

CA16-TYPE TRANSPONDER

TRANSMISSION LINES

Ω IMPEDANCE

TRANSMISSION LINES

INTERFACE IC

(LVPECL)

TxD[0:15]N

(LVPECL)

RxD[0:15]P

(LVPECL)

RxD[0:15]N

(LVPECL)

MUX

DEMUX

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