VITESSE

SEMICONDUCTOR CORPORATION

Data Sheet

VSC7121

Quad Port Bypass Circuit for 1.0625 Gbit/sec

Fibre Channel Arbitrated Loop Disk Arrays

Page 8

© VITESSE SEMICONDUCTOR CORPORATION

741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896

8/31/98

G52110-0, Rev. 4.1

Package Pin Description

Table 4: Pin Description

Pin #

Name

Description

9, 10

IN-, IN+

INPUT - Differential (Biased at VDD/2). Differential inputs from the downstream PBC

port.

3, 4

L_SI1-, L_SI1+

INPUT - Differential (Biased at VDD/2). Serial input from the local transmitter on PBC

port 1.

40, 41

L_SI2-, L_SI2+

INPUT - Differential (Biased at VDD/2). Serial input from the local transmitter on PBC

port 2.

34, 35

L_SI3-, L_SI3+

INPUT - Differential (Biased at VDD/2). Serial input from the local transmitter on PBC

port 3.

27, 28

L_SI4-, L_SI4+

INPUT - Differential (Biased at VDD/2). Serial input from the local transmitter on PBC

port 4.

15-18

SEL1, SEL2,

SEL3, SEL4

INPUT - TTL. A LOW selects the “BYPASS” mode causing the output of the previous

port to propagate to next port or OUT. When HIGH, this signal selects “NORMAL”

mode which routes the previous port to the local output, L_SOn, and routes the local

input, L_SIn, to the next port or OUT .

6, 7

L_SO1-,

L_SO1+

OUTPUT - Differential (Biased at VDD-1.32V).

Serial output driving the local receiver corresponding to PBC port 1.

43, 44

L_SO2-,

L_SO2+

OUTPUT - Differential (Biased at VDD-1.32V)

Serial output driving the local receiver corresponding to PBC port 2.

37, 38

L_SO3-,

L_SO3+

OUTPUT - Differential (Biased at VDD-1.32V)

Serial output driving the local receiver corresponding to PBC port 3.

30, 31

L_SO4-,

L_SO4+

OUTPUT - Differential (Biased at VDD-1.32V)

Serial output driving the local receiver corresponding to PBC port 4.

25, 24

OUT-, OUT+

OUTPUT - Differential (Biased at VDD - 1.32V) Serial output driving the upstream PBC

port.

2, 14, 20-21,

32

VDD

Digital Logic Power Supply. 3.3V Supply for digital logic.

5, 26, 29 36,

42

VDDP

High-Speed Output Power Supply. 3.3V Supply for PECL drivers.

1, 8, 11-13,

19, 22-23,

33, 39

VSS

Ground. Ground pins are physically attached to the die mounting surface, and are an

important part of the thermal path. For best thermal performance, all ground pins should

be connected to a ground plane, using multiple vias if possible.