xr
REV. P1.0.4
HARDWARE CONTROL
NAME
LEVEL
RLOOPS
LVTTL
RLOOPP
LVTTL
DLOOP
LVTTL
LPTIME_JA
LVTTL
LPTIME_NO_JA
LVTTL
PRELIMINARY
XRT91L80
2.488/2.666GBPS OC-48/STM-16 SONET/SDH TRANSCEIVER
TYPE
I
I
I
I
I
PIN
DESCRIPTION
C10 Serial Remote Loopback
Hardware Mode The serial remote loopback mode intercon-
nects the receive serial input data to the transmit serial output
data. If serial remote loopback is enabled, the 4-bit parallel
transmit input data is ignored while the 4-bit parallel receive
output data is maintained.
"Low" = Disabled
"High" = Serial Remote Loopback Mode Enabled
This pin is provided with an internal active pull-down.
NOTE: DLOOP and RLOOPS can be enabled simultaneously
to achieve a dual loopback diagnostic feature.
A11 Parallel Remote Loopback
Hardware Mode The parallel remote loopback mode allows the
input serial data stream to pass through the clock and data
recovery circuit and loopback at the parallel interface to the
serial output port. The 4-bit parallel transmit input data is
ignored while the 4-bit parallel receive output data is main-
tained.
"Low" = Disabled
"High" = Parallel Remote Loopback Mode Enabled
This pin is provided with an internal active pull-down.
NOTE: DLOOP and RLOOPS should be disabled when
RLOOPP is enabled.
B6 Digital Loopback
Hardware Mode The digital loopback mode interconnects the
4-bit parallel transmit input data and TxCLK to the 4-bit parallel
receive output data and RxCLK respectively while maintaining
the transmit serial output data. If digital loopback is enabled,
the receive serial input data is ignored.
"Low" = Disabled
"High" = Digital Loopback Mode Enabled
This pin is provided with an internal active pull-down.
NOTE: DLOOP and RLOOPS can be enabled simultaneously
to achieve a dual loopback diagnostic feature.
C6 Loop Timing Mode With Jitter Attenuation
The LPTIME_JA pin must be set "High" in order to select the
recovered receive clock as the reference source for the de-jitter
PLL.
"Low" = Disabled
"High" = Enabled
This pin is provided with an internal active pull-down.
P2 Loop Timing Mode With No Jitter Attenuation
When the loop timing mode is activated the external reference
clock to the input of the CMU is replaced with the 1/16th or the
1/32nd of the high-speed recovered receive clock from the
CDR.
"Low" = Disabled
"High" = Loop timing Activated
This pin is provided with an internal active pull-down.
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