1.6 GBPS QUAD SERIAL BACKPLANE DEVICE
S2009
Data Output
CHANNEL LOCKING/RE-LOCKING
PROCEDURE
Data is output on the DOUT[0:7] outputs. K-characters
are flagged using the KFLAG signal. The EOF (with
KFLAG) is used to indicate the reception of a valid
K28.5 character. Invalid codewords and decoding er-
rors are indicated on the ERR output. KFLAG, EOF,
and ERR are buffered with the data in the FIFO to
insure that all outputs are synchronized at the S2009
outputs. Errors are reported independently for each
channel in both Channel Lock Mode and Indepen-
dent Mode operation.
The channel locking/relocking procedures are sum-
marized below. Following these procedures will in-
sure proper Channel Lock operation of the device.
When powered up, the S2009 will lock to the re-
ceived data within approximately 2500 bit times. The
CRU must report lock for approximately 32,000
REFCLK periods (320 µs) before channel locking is
enabled.
1. Ensure that the S2009 is in the “No Sync” state.
This can be accomplished by resetting the device
(RESET_N Low) or by asserting TCLKD Low for
at least 16 clocks.
The S2009 TTL outputs are optimized to drive 65 Ω
line impedances. Internal source matching provides
good performance on unterminated lines of reason-
able length.
2. The transmitter portion of another S2009 device
initiates the appropriate synchronization se-
quence. Four or more K28.5 characters or the 16
word SYNC sequence followed by a valid non-
errored codeword (or data character) other than a
K28.5 can be used to de-skew the DOUT FIFOs.
In the transmitter, the 16 word SYNC character
can be generated by asserting SYNC=1 and
DN[A:D]=1. See the transmit portion of the speci-
fication for a complete description.
Parallel Output Clock Rate
Two output clock modes are supported, as shown in
Table 8. When CMODE is High, a complementary
TTL clock at the data rate is provided on the RCxP/N
outputs. Data should be clocked on the rising edge
of RCxP. When CMODE is Low, a complementary
TTL clock at 1/2 the data rate is provided. Data
should be latched on the rising edge of RCxP and
the rising edge of RCxN.
3. Wait for “Channel Lock Detected” as defined by
Table 7.
The S2009 follows the Gigabit Ethernet standard
which requires that the parallel clock output rate be
at half the word rate. In addition, the phase of the
RCxP/N clock must be adjusted such that the K28.5
appears on the rising edge of the RCxP signal. To
insure compatibility with the Gigabit Ethernet stan-
dard, the S2009 will buffer data such that this re-
quirement is met. This concept is referred to as data
stretching.
While in the “In Sync” state, the S2009 will enter the
“No Sync” state if: any CRU loses lock, if five or
more consecutive decoder errors are received, if the
decoder error rate exceeds 50% in a block of 16
bytes, if RESET_N is asserted Low, or if TCLKD is
asserted Low for at least 16 clocks. Note that if any
CRU has failed to lock to the incoming data, this will
be reported by the appropriate channel as “Loss of
Sync” and “Loss of Lock” (LOLx) (see Table 7). To
reacquire sync after moving to the “No Sync” state,
repeat steps 2 and 3 above.
In Gigabit Ethernet applications, multiple consecu-
tive K28.5 characters should not be generated. How-
ever, for serial backplane applications this can
occur. The S2009 must be able to operate properly
when multiple K28.5 characters are received. When
CMODE is Low, the S2009 guarantees that the last
K28.5 character before a non-K28.5 character will
always line up with the rising edge of RCxP. Be-
cause of this, the last data character or codeword
(including K28.5) prior to a sequence of one or more
K28.5 characters may be either duplicated or lost.
8B/10B Decoding
After serial to parallel conversion, the S2009 pro-
vides 8B/10B decoding of the data. The received 10-
bit code word is decoded to recover the original 8-bit
data. The decoder reports either invalid code word
errors or running disparity errors. Error type is deter-
mined by examining Table 7. When more than one
reportable condition occurs simultaneously, reporting
is in accordance with the rank assigned by Table 7.
15
February 9, 2001 / Revision C
AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
