XRT91L32 Просмотр технического описания (PDF) - Exar Corporation
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XRT91L32 Datasheet PDF : 37 Pages
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xr
REV. 1.0.2
NAME
CDRREFSEL
LEVEL
LVTTL
LOOPTIME
LVTTL
CDRDIS
LVTTL
VDD /
(PIO_CTRL )
LVTTL
TYPE
I
I
I
I
XRT91L32
STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER
PIN
DESCRIPTION
98 Clock and Data Recover Unit Reference Frequency Select
Selects the Clock and Data Recovery Unit reference frequency
based on the table below.
"Low" = CDR uses CMU’s reference clock
"High" = CDR reference clock from CDRAUXREFCLK
CDRREFSEL STS12/ CDRAUXREFCLK
STS3
FREQUENCY
DATA RATE
CDR uses CMU’s reference clock
0
(see CMUFREQSEL pin)
1
0
77.76 MHz
STS-3/STM-1
155.52 Mbps
1
1
77.76 MHz
STS-12/STM-4
622.08 Mbps
NOTE: CDRAUXREFCLK requires accuracy of 77.76 MHz
+/- 500ppm.
5
Loop Timing Mode
When the loop timing mode is activated the external reference
clock to the input of the Retimer is replaced with the high-speed
recovered receive clock from the CDR.
"Low" = Disabled
"High" = Loop timing Activated
23 Clock and Data Recovery Unit Disable
Active "High." Disables internal Clock and Data Recovery unit.
Received serial data bypasses the integrated CDR block.
RXINP/N is then sampled on the rising edge of externally
recovered differential clock XRXCLKIP/N coming from the opti-
cal module.
"Low" = Internal CDR unit is Enabled
"High" = Internal CDR unit is Disabled and Bypassed
81 Transmit Parallel Clock Directional Control
Transmit Parallel Clock Output Operation
If this pin is asserted "High", TXPCLK_IO is a parallel bus clock
output. Data on the TXDI[7:0] must be synchronously applied
prior to the sampling by the PISO at the rising edge of
TXPCLK_IO clock output driven by the XRT91L30.
RLOOPS
LVTTL
I
1
Serial Remote Loopback
The serial remote loopback mode interconnects the receive
serial data input to the transmit serial data output. If serial
remote loopback is enabled, the 8-bit parallel transmit data
input is ignored while the 8-bit parallel receive data output is
maintained.
"Low" = Disabled
"High" = Serial Remote Loopback Mode Enabled
NOTE: DLOOP and RLOOPS can be enabled simultaneously
to achieve a dual loopback diagnostic feature in normal
operation.
5
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