XRT73R12_07 Datasheet, PDF (6/89 Pages) Exar Corporation – TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT

XRT73R12
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT
PIN DESCRIPTIONS (BY FUNCTION)
REV. 1.0.2
SYSTEM-SIDE TRANSMIT INPUT AND TRANSMIT CONTROL PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
P4
TxON
I Transmit On/Off Input
Upon power up, the transmitters are powered on. Turning the transmitters
On or Off is selected through the microprocessor interface by programming
the appropriate channel register if this pin is pulled "High". If the TxON pin
is pulled "Low", all 12 transmitters are powered off.
NOTE: TxON is ideal for redundancy applications. See the R³
Technology section of this datasheet for more details.
Internally pulled "High".
F22
AA22
H22
Y23
G26
AA25
G1
AA2
H5
Y4
F5
AA5
TxCLK0
TxCLK1
TxCLK2
TxCLK3
TxCLK4
TxCLK5
TxCLK6
TxCLK7
TxCLK8
TxCLK9
TxCLK10
TxCLK11
I Transmit Clock Input
These input pins have three functions:
• They function as the timing source for the Transmit Section of the
corresponding channel within the XRT73R12.
• They are used by the Transmit Section of the LIU IC to sample the
corresponding TxPOS_n and TxNEG_n input pins.
• They are used to clock the PRBS generator
NOTE: The user is expected to supply a 44.736MHz ± 20ppm clock signal
(for DS3 applications), 34.368MHz ± 20 ppm clock signal (for E3
applications) or a 51.84MHz ± 4.6ppm clock signal (for STS-1,
Stratum 3E or better applications).
E23
AB24
J22
AA23
G25
AA26
G2
AA1
J5
AA4
E4
AB3
TxPOS0
TxPOS1
TxPOS2
TxPOS3
TxPOS4
TxPOS5
TxPOS6
TxPOS7
TxPOS8
TxPOS9
TxPOS10
TxPOS11
I Transmit Positive Data Input
The function of these digitial input pins depends upon whether the corre-
sponding channel has been configured to operate in the Single-Rail or
Dual-Rail Mode.
Single Rail Mode - Transmit Data Input
Operating in the Single-Rail Mode; all transmit input data will be serially
applied to this input pin. This signal will be latched into the Transmit Sec-
tion circuitry on the active edge of the TxCLK_n signal.
The Transmit Section of the LIU IC will then encode this data into either the
B3ZS line code (for DS3 and STS-1 applications) or the HDB3 line code
(for E3 applications).
Dual Rail Mode - Transmit Positive Data Input
In the Dual-Rail Mode, the user should apply a pulse to this input pin when
a positive-polarity pulse is to be transmitted onto the line. This signal will
be latched into the Transmit Section circuitry upon the active edge of the
TxCLK_n signal,.
The Transmit Section of the LIU IC will NOT encode this data into either the
B3ZS or HDB3 line codes. If the user configures the LIU IC to operate in
the Dual-Rail Mode, B3ZS/HDB3 encoding must have already been done
prior to this input.
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