VITESSE
SEMICONDUCTOR CORPORATION
Datasheet
2.5 Gbits/sec
34x34 Crosspoint Switch with Signal Detection
VSC835
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 ).
.
Table 2: Memory Map
Address
Access
Description
00h
01h
R/W
R/W
...
Output Y0’s programmed input channel (write and then assert CONFIG to program)
Output Y1’s programmed input channel
...
...
21h
R/W
R/O
R/O
R/O
R/O
R/O
Output Y33’s programmed input channel
22h, 23h
24h, 25h
26h, 27h
28h, 29h
2Ah
Rx Signal monitor for inputs [A0-A3], [A4-A7] (Logic ‘1’=No activity)
Rx Signal monitor for inputs [A8-A11], [A12-A15]
Rx Signal monitor for inputs [A16-A19], [A20-A23]
Rx Signal monitor for inputs [A24-A27], [A28-A31]
Rx Signal monitor for inputs [A32-A33]
AC Characteristics
Table 3: Data Path
Parameter
Description
Min
Typ
Max
Units
FRATE
TISKW
TOSKW
tR, tF
tR, tF
tjP
Data rate
-
-
-
-
-
-
-
300
300
-
2.5
-
Gbits/s
ps
Input channel delay skew (1)
Output channel delay skew (2)
-
ps
High-speed input rise/fall times, 20% to 80% (3)
High-speed output rise/fall times, 20% to 80%
Output data eye jitter, peak-peak, 231 PRBS (4)
150
150
100
ps
-
ps
-
ps
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 3: Required for high-speed output rise/fall spec at FRATE=2.5 Gbits/s. For lower rate signals, use 0.375/FRATE
note 4: Broadband jitter added to a jitter-free signal; jitter is primarily in the form of ISI for random data
Page 4
VITESSE SEMICONDUCTOR CORPORATION
G52270-0, Rev. 4.1
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896
7/24/00
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
