LXT6155LE datasheet(33/50 Pages) INTEL

33 / 50 page

Datasheet

155 Mbps SDH/SONET/ATM Transceiver — LXT6155

4.0

Application Information

The following provides application examples of interfacing the LXT6155 to the line side and the

overhead terminator side. Line side encoding schemes can be one of two types: LVPECL NRZ

encoded for a fiber optic module, or CMI encoded for a 75

Ω coax cable. On the systems side, serial

differential or parallel eight-bit modes can be used. All signals are TTL level compatible, except

serial interface signals (TPOS, TNEG, TSICLKP, TSICLKN, RSOCLKP, RSOCLKN, RPOS, and

RNEG) which are 3.3V LVPECL compatible.

4.1

Fiber Optic Module Interface

The LXT6155 is designed to directly drive a 3.3V LVPECL fiber optic transceiver. The LVPECL

drivers require the proper transmission line impedance to correctly drive the fiber module. Signal

traces should be 50

Ω controlled impedance lines and should be biased to the appropriate level.

Please refer to Figure 16 for the proper interface.

To interface the LXT6155 LVPECL signals to a 5V PECL fiber optic module, please refer to the

LXT6155 application note AN141.

4.2

Coax Interface

As shown in 17 on page 35, the LXT6155 directly drives a transformer connected to a 75

Ω coaxial

cable, up to12.7dB cable loss at 78MHz. This is approximately 110m of RG59U. Please refer to

manufacturers specifications for maximum cable lengths. Output CMI waveform conform to the

ITU G.703 specifications. Rise and fall times are less than 2.0 ns.

LXT6155LE Datasheet(PDF) 33 Page - Intel Corporation