XRT79L73 Datasheet, PDF (43/71 Pages) Exar Corporation – 3 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

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PRELIMINARY
3 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
XRT79L73
REV. P1.0.0
PIN #
Y1
AD10
AD14
AD6
AE10
AE14
AE6
AE2
Y23
AC3
NAME
E3CLK
TTIP1
TTIP2
TTIP3
TRING1
TRING2
TRING3
TAISEN1
TAISEN2
TAISEN3
TYPE
DESCRIPTION
I Clock Recovery PLL E3 Reference Clock Input:
The exact function of this input pin depends upon whether or not the XRT79L73
device has been configured to operate in the SFM (Single-Frequency Mode)
Mode, as described below.If the XRT79L73 device is NOT operating in the Single-
Frequency ModeIf the XRT79L73 device has NOT been configured to operate in
the SFM Mode, then this input pin will function as a Reference Clock signal for the
Clock Recovery PLL and the Jitter Attenuator PLL within the Receive DS3/E33
LIU Block, whenever the XRT79L73 device has been configured to operate in the
E3 Mode.
NOTE: For E3/Non-SFM Modes of operation, the user is expected to supply a
34.368MHz ± 20ppm clock signal to this input pin.
If the XRT79L73 device is operating in the Single-Frequency ModeIf the user has
configured the XRT79L73 device to operate in the SFM Mode, then the user
MUST apply a clock signal with a frequency of 12.288 ± 20ppm to the "DS3CLK/
SFMCLK" input pin (Ball P16). Additionally, the user MUST tie this input pin to
GND.
NOTE: If the user only intends to operate the XRT79L73 device in the DS3/Non-
SFM Mode, then the user should tie this input pin to GND.
O Transmit Output - Positive Polarity Signal:
O These output pins, along with the TRING output pins, function as the Transmit
O ^{DS3/E3 output signal drivers for the XRT79L73.}
The user is expected to connect these signals and the TRING output signals to a
1:1 transformer.
Whenever the Transmit Section of the XRT79L73 generates and transmits a posi-
tive-polarity pulse onto the line, these output pins will be pulsed to a "higher-volt-
age" than the TRING output pins.
Conversely, whenever the Transmit Section of the XRT79L73 generates and
transmit a negative-polarity pulse onto the line, these output pins will be pulsed to
a "lower-voltage" than the TRING output pins.
NOTE: These output pins will be tri-stated whenever the user sets the TxONn
input pin (or bit-field) to "0".
O Transmit Output - Negative Polarity Signal:
O These output pins along with the TTIP output pins, function as the Transmit DS3/
O ^{E3 output signal drivers for the XRT79L73.}
The user is expected to connect these signals and the TTIP output signals to a 1:1
transformer.
Whenever the Transmit Section of the XRT79L73 generates and transmits a pos-
itive-polarity pulse onto the line, these output pins will be pulsed to a "lower-volt-
age" than the TTIP output pins.
Conversely, whenever the Transmit Section of the XRT79L73 generates and
transmit a negative-polarity pulse onto the line, these output pins will be pulsed to
a "higher-voltage" than the TTIP output pins.
NOTE: These output pins will be tri-stated whenever the user sets the TxONn
input pin (or bit-field) to "0".
I Transmit Alarm Indication Signal Enable Input
I
I
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