1.6 GBPS QUAD SERIAL BACKPLANE DEVICE
S2009
Figure 6. DINx Data Clocking with TCLK
Half Rate Operation
The S2009 supports full and 1/2 rate operation for all
modes of operation. When RATE is Low, the S2009
serial data rate equals the VCO frequency. When
RATE is High, the VCO is divided by 2 before being
provided to the chip. The half rate range for the serial
data will be between 650 and 800 MHz. Thus the
S2009 can support serial backplane functions at both
full and 1/2 the VCO rate. See Table 5.
VCO/20
REF
OSCILLATOR
REFCLK
TCLKO
PLL
8B/10B Coding
DINx[0:7]
The S2009 provides 8B/10B line coding for each
channel. 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 char-
acters defined by this code ensure that enough tran-
sitions are present in the serial bit stream to make
clock recovery possible at the receiver. The encod-
ing also greatly increases the likelihood of detecting
any single or multiple errors that might occur during
the transmission and reception of data1.
TCLKx
MAC
ASIC
S2009
Figure 6 demonstrates the flexibility afforded by the
S2009. A low jitter reference is provided directly to the
S2009 at 1/20 the serial data rate. Two system clock
outputs are provided from the S2009 at both the par-
allel word rate (TCLKO) and the parallel word rate
divided by two (TCLKO2). These two outputs are de-
rived from the PLL and are provided to the upstream
circuit as system clocks. The frequency of the TCLKO
output is constant at the parallel word rate, 1/10 the
serial data rate. The TCLKO2 frequency is constant at
the parallel word rate divided by two, 1/20 the serial
data rate. These clocks can be buffered as required
without concern about added delay. There is no
phase requirement between TCLKO or TCLKO2 and
TCLKx, which are provided back to the S2009, other
than that the output clock that is chosen and TCLKx
remain within ± 3 ns of the phase relationship estab-
lished at reset.
The 8B/10B transmission code includes D-charac-
ters, used for data transmission, and K-characters,
used for control or protocol functions. Each D-char-
acter and K-character has a positive and a negative
parity version. The parity of each codeword is se-
lected by the encoder to control the running disparity
of the data stream. K-character generation is con-
trolled individually 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 running disparity in the serial
data stream. Table 3 lists the K characters sup-
ported by the S2009 and identifies the mapping of
the DIN[7:0] bits to each character.
1
1. A.X. Widner and P.A. Franaszek, "A Byte-Oriented DC Bal-
anced (0,4) 8B/10B Transmission Code," IBM Research Report
RC9391, May 1982.
7
February 9, 2001 / Revision C
AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
