900,000+ datasheet pdf search and download

Datasheet4U offers most rated semiconductors data sheet pdf






Vitesse Semiconductor

VSC7121 Datasheet Preview

VSC7121 Datasheet

Quad Port Bypass Circuit

No Preview Available !

www.DataSheet4U.com
VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC7121
Quad Port Bypass Circuit for 1.0625 Gbit/sec
Fibre Channel Arbitrated Loop Disk Arrays
Description
• Supports ANSI X3T11 1.0625 Gbit/sec
FC-AL Disk Attach for Resiliency
• Fully Differential for Minimum
Jitter Accumulation.
• Quad PBC’s in Single Package
• TTL Bypass Select
• High Speed, PECL I/O’s Referenced to VDD.
• 0.5W Typical Power Dissipation
• 3.3V Power Supply
• 44-Pin, 10mm PQFP
The VSC7121 is a Quad Port Bypass Circuit (PBC). Four Fibre Channel PBC’s are cascaded into a single
part to minimize part count, cost, high frequency routing, and jitter accumulation. Port Bypass Circuits are used
to provide resiliency in Fibre Channel Arbitrated Loop (FC-AL) architectures. PBC’s are used within FC-AL
disk arrays to allow for resiliency and hot swapping of FC-AL drives.
A Port Bypass Circuit is a 2:1 Multiplexer with two modes of operation: NORMAL and BYPASS. In NOR-
MAL mode, the disk drive is connected to the loop. Data goes from the 7121’s L_SOn pin to the Disk Drive RX
input and data from the disk drive TX output goes to the 7121’s L_SIn pin. Refer to Figure 2 for disk drive
application. In BYPASS mode, the disk drive is either absent or non-functional and data bypasses to the next
available disk drive. Normal mode is enabled with a HIGH on the SEL pin and BYPASS mode is enabled by a
LOW on the SEL pin. Direct Attach Fibre Channel Disk Drives have an “LRC Interlock” signal defined to con-
trol the SEL function.
Using a VSC7121 in a single loop of a disk array is illustrated in Figure 2: “Disk Array Application”. FC-
AL drives are all expected to be dual loop. The VSC7121 is cascaded in a manner such that all the 7121’s inter-
nal PBC’s are used in the same loop. For dual loop implementations, two or more VSC7121’s should be used.
Allocating each VSC7121 to only one of two loops preserves redundancy, prevents a single point of failure and
lends itself to on-line maintainability.
7121 Block Diagram
1 11 1
IN+
IN-
0 00 0
PBC1
PBC2
PBC3
PBC4
OUT+
OUT-
The VSC7121 can be cascaded through the IN and OUT pins for arrays of disk drives greater than 4. For
disk arrays with a noninteger multiple of 4 disk drives, the unused PBC’s can be hardwired to bypass with a
external pulldown resistor.
G52110-0, Rev. 4.1
8/31/98
© VITESSE SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896
Page 1




Vitesse Semiconductor

VSC7121 Datasheet Preview

VSC7121 Datasheet

Quad Port Bypass Circuit

No Preview Available !

VITESSE
SEMICONDUCTOR CORPORATION
Quad Port Bypass Circuit for 1.0625 Gbit/sec
Fibre Channel Arbitrated Loop Disk Arrays
Data Sheet
VSC7121
Table 1 is a truth table detailing the data flow through the VSC7121. Figure 1 shows a timing diagram of the
data relationship in the VSC7121. There are no critical timing (setup, hold, or delay) parameters for the
VSC7121 as this part routes the serial data encoded with the baud clock that is extracted by a Fibre Channel
receiver. The primary AC parameter of importance is the jitter or data eye degradation inserted by the port
bypass circuit. The design of the VSC7121 minimizes jitter accumulation by using fully differential circuits.
This provides for symmetric rise and fall delays as well as noise rejection.
Table 1: Truth Table
SEL1
L
L
L
L
H
H
SELECT STATE
SEL2
SEL3
LL
LL
LH
HL
LL
HH
SEL4
L
H
L
L
L
H
OUT
IN
SI4
SI3
SI2
SI1
SI4
DATA OUTPUTS
SO4 SO3 SO2
IN IN IN
IN IN IN
SI3 IN
IN
SI2 SI2 IN
SI1 SI1 SI1
SI3 SI2 SI1
SO1
IN
IN
IN
IN
IN
IN
IN+/-
LSI1+/-
LSI2+/-
LSI3+/-
LSI4+/-
Figure 1: Timing Waveforms
OUT+/-
LSO1+/-
LSO2+/-
LSO3+/-
LSO4+/-
T1
T2 Tjitter
Page 2
© VITESSE SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896
G52110-0, Rev. 4.1
8/31/98


Part Number VSC7121
Description Quad Port Bypass Circuit
Maker Vitesse Semiconductor
PDF Download

VSC7121 Datasheet PDF





Similar Datasheet

1 VSC7121 Quad Port Bypass Circuit
Vitesse Semiconductor
2 VSC7123 10-Bit Transceiver for Fibre Channel and Gigabit Ethernet
ETC
3 VSC7125 1.0625 Gbits/sec Fibre Channel Transceiver
ETC





Part Number Start With

0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F    G    H    I    J    K    L    M    N    O    P    Q    R    S    T    U    V    W    X    Y    Z

Site map

Webmaste! click here

Contact us

Buy Components

Privacy Policy