78P2351R-IM 查看數據表（PDF） - Teridian Semiconductor Corporation

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78P2351R-IM

Serial 155M NRZ to CMI Converter

Teridian Semiconductor Corporation 

Pulse Amplitude Adjustment

Contact TDK applications for information on user

programmable registers with up to 200mV of

programmable transmit gain.

Transmit Backplane Equalizer

An optional fixed LVPECL equalizer is integrated in

the transmit path for architectures that use LIUs on

active interface cards. The fixed equalizer can

compensate for up to 1.5m of trace and can be

enabled by the TXOUT1 pin or TXEQ bit as follows:

TXOUT1 pin

Low

Float

TXEQ bit

1

0

Tx Equalizer

Enabled

Disabled

POWER-DOWN FUNCTION

Power-down control is provided to allow the

78P2351R to be shut off. Transmit and receive

power-down can be set independently through SW

control. Global power-down is achieved by

powering down both the transmitter and receiver.

Note: the 4-wire serial port interface and

configuration registers are not affected by power-

down.

The transmitter can also be powered down using the

TXPD control pin. The CMI outputs are tri-stated

during transmit power-down for redundancy

applications. The TXPD pin is active in both

hardware and software modes.

LOOPBACK MODES

In SW mode, LLBK and RLBK bits in the Signal

Control register are provided to activate the local

and remote analog loopback modes respectively.

In HW mode, the LPBK pin can be used to activate

local and remote analog loopback paths as shown in

the table below.

LPBK pin

Low

Float

High

Loopback Mode

Normal operation

Remote (analog) Loopback:

Recovered receive clock and data

looped back directly to the transmit

driver. The CMI decoder and most of

transmit path is bypassed (including the

redundant Tx monitor output)

Local (analog) Loopback:

Transmit clock and data looped back to

receiver at the analog media interface.

78P2351R

Serial 155M

NRZ to CMI Converter

Line-side

Adaptive

Eq.

CDR

CDR

Fixed

Eq.

CMI

ENDEC

TD +

TD -

RD +

RD -

Figure 3: Remote (analog) Loopback

Adaptive

Eq.

CDR

CDR

Fixed

Eq.

CMI

ENDEC

TD +

TD -

RD +

RD -

Figure 4: Local (analog) Loopback

In SW mode only, a Full Remote (digital) Loopback

bit FLBK is also available in the Advanced Tx

Control register. This loopback exercises the entire

Rx and Tx paths of the 78P2351 including the Tx

clock recovery unit. As such, the user must enable

either Plesiochronous or Loop-timing transmit modes

to utilize the Full Remote (digital) Loopback.

Line-side

Adaptive

Eq.

CDR

CDR

Fixed

Eq.

CMI

ENDEC

TD +

TD -

RD +

RD -

Figure 5: Remote (Digital) Loopback

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2006 Teridian Semiconductor Corporation

Rev. 2.1

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