Revision J – April 7, 2006
S2004 – Quad Serial Backplane Device
Data Sheet
Figure 6. DINx Data Clocking with TCLK
Figure 7. DIN Clocking with REFCLK
VCO/10
VCO/10 or VCO/20
REF
REF
OSCILLATOR
OSCILLATOR
REFCLK
REFCLK
PLL
TCLKO
TCLKO
PLL
DINx[0:7]
DINx[0:7]
TCLKx
TCLKx
MAC
ASIC
MAC
ASIC
S2004
S2004
The S2004 also supports the traditional REFCLK
(TBC) clocking found in many Fibre Channel and
Gigabit Ethernet applications and is illustrated in Fig-
ure 7.
greatly increases the likelihood of detecting any single
or multiple errors that might occur during the transmis-
sion and reception of data .
1
The 8B/10B transmission code includes D-characters,
used for data transmission, and K-characters, used for
control or protocol functions. Each D-character and K-
character has a positive and a negative parity version.
The parity of each codeword is selected by the
encoder to control the running disparity of the data
stream. K-character generation is con-trolled individu-
ally for each channel using the KGENx input. When
KGEN is asserted the data on the parallel input is
mapped into the corresponding control character. The
parity of the K-character is selected to minimize run-
ning disparity in the serial data stream. Table 3 lists the
K characters sup-ported by the S2004 and identifies
the mapping of the DIN[7:0] bits to each character.
Half Rate Operation
The S2004 supports full and 1/2 rate operation for all
modes of operation. When RATE is LOW, the S2004
serial data rate equals the VCO frequency. When
RATE is HIGH, the VCO is divided-by-2 before being
provided to the chip. Thus the S2004 can support
Fibre Channel and serial backplane functions at both
full and 1/2 the VCO rate. (See Table 5.)
8B/10B Coding
The S2004 provides 8B/10B line coding for each chan-
nel. The 8B/10B transmission code includes se-rial
encoding and decoding rules, special characters, and
error control. Information is encoded, 8 bits at a time,
into a 10 bit transmission character. The characters
defined by this code ensure that enough transitions
are present in the serial bit stream to make clock
recovery possible at the receiver. The encoding also
1.
A.X. Widner and P.A. Franaszek, "A Byte-Oriented DC
Balanced (0,4) 8B/10B Transmission Code," IBM Re-
search Report RC9391, May 1982.
10
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AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
