
1
SIX PORT BYPASS AND REPEATER FOR FC-AL
S2074
S2074
February 9, 2000 / Revision D
FEATURES
ANSI X3T11 Fibre Channel Compliant
Monolithic Clock Recovery Unit
– Retimes & Buffers Received Data
– Jitter Peaking < 0.1 dB
Lock Detect Function
– Frequency Detection
Six Port Bypass Circuits
Suitable for both Coaxial and Optical Link
Low Power Operation 0.98 W Typical
106.25 or 53.125 MHz Reference Clock
Compact 14 mm x 14 mm 64 Pin
PQFP Package
3.3 V Supply
Micropower Bipolar Technology
APPLICATIONS
FC-AL Nodes
RAID
JBOD
SAN
GENERAL DESCRIPTION
The Six Port Bypass and Repeater for FC-AL Circuit
is used in full-speed (1.0625 Gb/s) Disk Arrays. It
contains a monolithic Clock Recovery Unit (CRU), a
lock detect feature and six port bypass circuits. The
S2074 may be used to implement a single chip Arbi-
trated Loop Port Bypass Retiming Node. The S2074
Figure 1. S2074 Functional Block Diagram
DEVICE
SPECIFICATION
performs the function of six port bypass circuits fol-
lowed by a Clock and Data Retimer (CDR). The
CDR retimes incoming serial data, detects whether a
valid signal is present and outputs a low jitter serial
data stream.
FUNCTIONAL DESCRIPTION
The S2074 Functional Block Diagram is shown in
Figure 1. The S2074 performs two functions. The
first function is a six Port Bypass Circuit (PBC) for
nodes in a FC-AL system. The low jitter accumula-
tion of the port bypass path is essential in these
systems. The second function is to restore signal
quality in RAID drives using the FC-AL link configu-
ration. The S2074 clock and data recovery PLL pro-
vides low jitter transfer peaking and the high jitter
tolerance. In addition, the lock detect circuit monitors
the incoming signals for frequency, which is useful
for link performance monitoring and detection of
channel present.
Jitter Performance
Input jitter tolerance is defined as the amplitude of
frequency dependent, random and deterministic jitter
that causes the clock recovery PLL to violate the
BER specifications.
The S2074 complies with the minimum jitter toler-
ance requirements proposed by the Fibre Channel
jitter working group when used with differential in-
puts and outputs as shown in Figure 2. In addition,
the S2074 is designed for minimum jitter generation
and jitter transfer specifications. This allows the opti-
mum system design for arbitrated loop architectures.
0
1
0
1
0
1
0
1
DDO0 DDI0
EN0
DDO1
DDI1
EN1
DDO2
DDI2
EN2
DDO3 DDI3
EN3
0
1
DDO4
DDI4
EN4
0
1
DDO5 DDI5
EN5
IN
CDR
OUTP/N
LOCKDET
B
R
L
R
L
L