78P2344JAT datasheet(2/37 Pages) TERIDIAN

2 / 37 page

78P2344JAT

4-port E3/DS3/STS-1 LIU

with Jitter Attenuator

Page 2 of 37

2005 Teridian Semiconductor Corporation

Rev 2.2

FUNCTIONAL DESCRIPTION

The

78P2344JAT

contains

all

the

necessary

transmit

and

receive

circuitry

for

connection

between E3, DS3, or STS-1 line interfaces and

digital Framer/Mapper ICs.

OPERATING RATE

The Master Control Register (MSCR) determines

which mode the device operates in according to the

table below.

The MSL0 pin is also provided for

mode selection in applications without a serial

control interface. Upon power-up or reset, the state

of the MSL0 pin is sensed and mapped into the DS3

and E3 register bits representing the appropriate

mode of operation. After power-up/reset, the state of

the MSL0 pin is ignored.

Standard

MSL0 pin

DS3 bit

E3 bit

DS3

STS-1

RECEIVER OPERATION

The receiver input is either transformer-coupled or

capacitor-coupled to the line signal. In applications

where the highest performance and isolation are

required, a 1:1 transformer is used in the receive

path. In applications where isolation is provided

elsewhere in the circuit, capacitor coupling can be

used. The receiver input should be line terminated

externally with a termination resistor.

The AMI signal first enters an AGC, which has a

selectable gain range setting. In normal operation,

the AGC can compensate for signals with up to 6dB

of flat loss.

When Receiver Monitor Mode is

enabled, the AGC can compensate for a DSX3

monitor signal with 16 to 20 dB of flat loss.

The

signal then enters a high performance adaptive

equalizer.

The equalizer is designed to overcome

inter-symbol interference caused by long cable

lengths.

Because the equalizer is adaptive, the

circuit will work with all square-shaped signals such

as DS3-high or 34.368 Mbit/s E3. The variable gain

differential amplifier automatically controls the gain

maintain

constant

voltage

level

output

regardless of the input voltage level.

The jitter tolerance of 78P2344JAT meets the

requirements of ITU-T G.823 for E3 rates; the

requirements of ITU-T G.824 and Telcordia GR-499

(Cat I and II) for DS3 rates; and the requirements of

Telcordia GR-253 for STS1 rates.

With the Jitter Attenuator disabled, the jitter transfer

function meets the requirements of GR-499 for

Category II DS3 interfaces.

When

the

Jitter

Attenuator

enabled,

the

78P2344JAT meets the requirements of GR-499

and

GR-253

for

all

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