XRT83VSH28IB datasheet(17/74 Pages) EXAR

17 / 74 page

PRELIMINARY

XRT83VSH28

REV. P1.0.0

8-CHANNEL E1 SHORT-HAUL LINE INTERFACE UNIT

ALARM FUNCTIONS/REDUNDANCY SUPPORT

SIGNAL NAME

BGA

LEAD #

TYPE

DESCRIPTION

GAUGE

J18

Twisted Pair Cable Wire Gauge Select

Hardware Mode Only

This pin is used to match the frequency characteristics according to the gauge of

wire used in Telecom circuits. By default, the LIU is matched to 22 gauge or 24

gauge wire. To select 26 gauge, this pin must be pulled "High".

NOTE: Internally pulled “Low” with a 50k

Ω resistor.

DMO0

DMO1

DMO2

DMO3

DMO4

DMO5

DMO6

DMO7

C15

C13

U17

V14

Digital Monitor Output

When no transmit output pulse is detected for more than 128 TCLK cycles within the

transmit output buffer, the DMO pin will go "High" for a minimum of one TCLK cycle.

DMO will remain "High" until the transmitter sends a valid pulse.

NOTE: This pin can be used for redundancy applications to initiate an automatic

switch to a backup card.

RESET

Hardware Reset Input

Active low signal. When this pin is pulled "Low" for more than 10µS, the internal reg-

isters are set to their default state. See the register description for the default val-

ues.

NOTE: Internally pulled "High" with a 50K

Ω resistor.

SR/DR

Single-Rail/Dual-Rail Data Format

Hardware Mode Only

This pin is used to control the data format on the facility side of the LIU to interface to

a Framer or Mapper/ASIC device. By default, dual rail mode is selected which relies

upon the Framer to handle the encoding/decoding functions. To select single rail

mode, this pin must be pulled "High". If single rail mode is selected, the LIU can

encode/decode AMI or HDB3 data formats.

NOTE: Internally pulled “Low” with a 50k

Ω resistor.

RXTSEL

U11

Receiver Termination Select

Hardware Mode

This pin is used to select between the internal and external impedance modes for

the receive path. By default, the receivers are configured for external impedance

mode, which is ideal for redundancy applications without relays. To select internal

impedance, this pin must be pulled "HIgh".

Host Mode

Internal/External impedance can be selected by programming the appropriate chan-

nel registers. However, to assist in redundancy applications, this pin can be used for

a hard switch if the RxTCNTL bit is set "High" in the appropriate global register. If

RxTCNTL is set "High", the individual RxTSEL register bits are ignored.

NOTE: This pin is internally pulled “Low” with a 50k

Ω resistor.

TXTSEL

V11

Transmitter Termination Select

Hardware Mode

This pin is used to select between the internal and external impedance modes for

the transmit path. By default, the receivers are configured for external impedance

mode, which is ideal for redundancy applications without relays. To select internal

impedance, this pin must be pulled "HIgh".

NOTE: This pin is internally pulled "Low".

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