XRT74L74 Datasheet, PDF (23/498 Pages) Exar Corporation – 4 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

PRELIMINARY
PIN DESCRIPTION
PIN#
NAME
A22
TAOS_0
C21
TAOS_1
B21
TAOS_2
A21
TAOS_3
B9
ENDECDIS_0
A9
ENDECDIS_1
D9
ENDECDIS_2
B8
ENDECDIS_3
XRT74L74
4 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.1.1
TYPE
O
O
DESCRIPTION
Transmit All Ones Signal (TAOS) Command (for the XRT73L04 LIU IC).
These output pins are intended to be connected to each of the TAOS input pins
of the XRT73L04 device. The user can control the state of these output pins by
writing a "0" or "1" into Bit 4 (TAOS) within the corresponding Line Interface Drive
Register (Address = 0xXX, 0xXX). If the user commands this signal to toggle
"high", then it will force the corresponding channel (within the XRT73L04 device)
to transmit an "All Ones" pattern onto the line. Conversely, if the user commands
this output signal to toggle "low", then the corresponding channel will proceed to
transmit data based upon the data that it receives via the TxPOS and TxNEG
output pins (of the XRT74L74 device).
Writing a "1" to Bit 4 of the Line Interface Drive Register will cause this output pin
to toggle "high". Writing a "0" to this bit-field will cause this output pin to toggle
"low".
NOTE: If the designer is not using the XRT73L04 DS3/E3/STS-1 LIU IC, then
this output pin can be used for other purposes
Encoder/Decoder (B3ZS & HDB3) Disable Output pin (intended to be con-
nected to the XRT73L04 DS3/E3/STS-1 LIU IC):
These output pins are intended to be connected to each of the ENDECDIS input
pins of the XRT73L04 LIU IC. The user can control the state of this output pin by
writing a "0" or "1" into Bit 3 (ENDECDIS) within the Line Interface Drive Register
(Address = 0xXX, 0xXX). If the user commands this signal to toggle "high", then
it will disable the B3ZS/HDB3 Encoder and Decoder circuitry within the corre-
sponding channel (within the XRT73L04 device). Conversely, if the user com-
mands this output signal to toggle "low", then the B3ZS/HDB3 Encoder and
Decoder circuitry, within the corresponding LIU channel will be enabled.
Writing a "1" to Bit 3 of the Line Interface Drive Register will cause this output pin
to toggle "high". Writing a "0" to this bit-field will cause this output pin to toggle
"low".
NOTES:
1. The user is advised to disable the B3ZS/HDB3 Encoder and Decoder
(within the XRT73L04 LIU IC) if the B3ZS/HDB3 Encoder and Decoder
blocks (within the XRT74L74 device) are enabled.
2. If the designer is not using the XRT73L04 DS3/E3/STS-1 LIU IC, then
this output pin can be used as a General Purpose Output pin
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