XRT91L31_08 Datasheet, PDF (27/41 Pages) Exar Corporation – STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER

XRT91L31
REV. 1.0.2
STS-12/STM-4 OR STS-3/STM-1 SONET/SDH TRANSCEIVER
TABLE 14: ALTERNATE TRANSMIT PARALLEL DATA INPUT TIMING (STS-12/STM-4 OPERATION)
SYMBOL
t_{TXPCLK_IO}
t_{TXDI_SU}
t_{TXDI_HD}
PARAMETER
Transmit Clock Input period
Transmit data setup time with respect to TXPCLK_IO
Transmit data hold time with respect to TXPCLK_IO
MIN
TYP
12.86
2.0
1.0
MAX
UNITS
ns
ns
ns
TABLE 15: ALTERNATE TRANSMIT PARALLEL DATA INPUT TIMING (STS-3/STM-1 OPERATION).
SYMBOL
t_{TXPCLK_IO}
t_{TXDI_SU}
t_{TXDI_HD}
PARAMETER
Transmit Clock Input period
Transmit data setup time with respect to TXPCLK_IO
Transmit data hold time with respect to TXPCLK_IO
MIN
TYP
51.44
2.0
1.0
MAX
UNITS
ns
ns
ns
3.5 Transmit Parallel Input to Serial Output (PISO)
The PISO is used to convert 77.76 Mbps or 19.44 Mbps parallel data input to 622.08 Mbps STS-12/STM-1 or
155.52 Mbps STS-3/STM-1 serial data output respectively, which can interface to an optical module. The
PISO bit interleaves parallel data input into a serial bit stream taking the first bit from TXDI7, then the first bit
from TXDI6, and so on as shown in Figure 15.
FIGURE 15. SIMPLIFIED BLOCK DIAGRAM OF PISO
TXDI0
8-bit Parallel LVTTL Input Data
b07 b06 b05 b04 b03 b02 b01 b00
TXDI_n
bn7 bn6 bn5 bn4 bn3 bn2 bn1 bn0
TXDI_n+
bn+7 bn+6 bn+5 bn+4 bn+3 bn+2 bn+1 bn+0
TXDI7
b77 b76 b75 b74 b73 b72 b71 b70
time (0)
622.08 Mbps STS-12/STM-4 or
155.52 Mbps STS-3/STM-1 serial data rate
b70 b60 b50 b40 b30 b20
b77 b67 b57 b47 b37 b27 b17 b07
TXPCLK_IO
77.76 MHz (STS-12/STM-4) or 19.44 MHz (STS-3/STM-1)
TXOP/N
27