LXT6155LE datasheet(21/50 Pages) INTEL

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Datasheet

155 Mbps SDH/SONET/ATM Transceiver — LXT6155

2.5.1.2

Loopback Test (RLIS and LLIS pins)

The LXT6155 allows two types of loopback test: Remote loopback and Local loopback. In Remote

loopback, the received data and clock are looped back to the transmit line interface. The LXT6155

still outputs recovered data and clock at the system interface. In Local loopback, the transmit data

is looped back to the receive input at the line interface. The LXT6155 also transmit data onto the

line interface while looping back. For descriptive diagrams, please refer to Figures 13 and 14.

2.5.1.3

Line Interface Selection (MODE Pin)

The MODE pin sets one of the two line interfaces, as described in Table 5.

2.5.1.4

Parallel/Serial Mode Selection (SP pin)

In Hardware Mode, HWSEL = Low, the LXT6155 can be set to operate in serial or parallel data

mode, depending on how the Serial/Parallel SP pin is set.

Setting the SP pin = High sets the LXT6155 to an 8-bit parallel mode. Parallel pins TPID<7:0>,

TPICLK, RPOD<7:0>, ROFP, RPOCLK, LOCK and LOS are be used. Serial pins TPOS, TNEG,

TSICLKP, TSICLKN, RPOS, RNEG, RSOCLKP, RSOCLKN are unused and should be left open.

Setting the SP pin = Low sets the LXT6155 to serial mode. Pins TPOS, TNEG, TSICLKP,

TSICLKN, RPOS, RNEG, RSOCLKP, RSOCLKN, LOCK and LOS are used. Pins TPID<7:0>,

TPICLK, RPOD<7:0> and RPOCLK are unused and should be left open.

2.5.1.5

Tx Amplitude Trim

In Hardware, serial, coax mode, the line driver output amplitude can be controlled via pins 16 to

20. Setting TXTRIMENA (pin #20) high enables the trim capability. The trim rage is -21% to

+24% in 3% steps controlled by TXTRIM0-TXTRIM3. The minimum amplitude is at 0000 and the

maximum amplitude is at 1111. This is the same control range as in SW mode.

Table 4.

Loopback Selection

RLIS

LLIS

Description

Low

Normal operation. No loopback testing.

Low

High

Local loopback test activate.

High

Low

Remote loopback test activate.

High

Table 5.

MODE Line Interface Settings

MODE

Description

Low

Sets LVPECL NRZ mode to interface to a fiber

optic module. CMI related blocks (e.g. input/output

buffers, equalizer) are disabled.

High

Sets CMI mode to interface to a transformer and a

Ω coax cable. NRZ related input/output buffers

are disabled.

LXT6155LE Datasheet(PDF) 21 Page - Intel Corporation

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