VITESSE

SEMICONDUCTOR CORPORATION

Datasheet

VSC835

2.5 Gbits/sec

34x34 Crosspoint Switch with Signal Detection

Page 4

© VITESSE SEMICONDUCTOR CORPORATION

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

7/24/00

G52270-0, Rev. 4.1

If any change in a monitor state occurs after sampling by MONCLK, an interrupt will be signalled by

asserting INTB, and the user must identify the offending channel by reading the monitor states. The interrupt

will be cleared when the corresponding activity monitor is read, but the monitor state will not be changed. If

multiple monitors have triggered the interrupt, it will persist until all the corresponding monitors have been

read.

LOA requires a minimum signal level of 30-150mV peak-peak to recognize an input as active. This is

required to distinguish noise on an unconnected signal (where both inputs float to the termination voltage) from

activity on a live signal. A minimum of two transitions defines activity. The threshold signal level is controlled

by the voltage on the VHYS pin. In order to keep the hysteresis in a useful range, it is recommended that VHYS

be nominally tied to VCC (useful range is 2.0V to VCC ).

.

AC Characteristics

note: Unless otherwise stated, all specifications are guaranteed but not tested.

note 1: Skew between any two input channels to a given output.

note 2: Skew between any two output channels from the same input channel.

note 4: Broadband jitter added to a jitter-free signal; jitter is primarily in the form of ISI for random data

Table 2: Memory Map

Address

Access

Description

00h

R/W

Output Y0’s programmed input channel (write and then assert CONFIG to program)

01h

R/W

Output Y1’s programmed input channel

...

...

...

21h

R/W

Output Y33’s programmed input channel

22h, 23h

R/O

Rx Signal monitor for inputs [A0-A3], [A4-A7]

(Logic ‘1’=No activity)

24h, 25h

R/O

Rx Signal monitor for inputs [A8-A11], [A12-A15]

26h, 27h

R/O

Rx Signal monitor for inputs [A16-A19], [A20-A23]

28h, 29h

R/O

Rx Signal monitor for inputs [A24-A27], [A28-A31]

2Ah

R/O

Rx Signal monitor for inputs [A32-A33]

Table 3: Data Path

Parameter

Description

Min

Typ

Max

Units

Data rate

-

-

2.5

Gbits/s

Input channel delay skew (1)

-

300

-

ps

Output channel delay skew (2)

-

300

-

ps

High-speed input rise/fall times, 20% to 80% (3)

-

-

150

ps

High-speed output rise/fall times, 20% to 80%

-

-

150

ps

-

-

100

ps