VITESSE
SEMICONDUCTOR CORPORATION
2.5Gb/s 17x17 Crosspoint Switch
with Input Signal Activity (ISA) Monitoring
Datasheet
VSC834
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.
The LOA circuitry requires a minimum signal level of 30-150 mV 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 can be adjusted with the VHYS pin, which can set the threshold from zero to the maximum allowed input
swing. The VHYS pin will self-bias to a nomial value that will be appropriate for most applications (30-150mV
p-p input level). Although uncalibrated for nominal level, gain and linearity, the VHYS pin can be externally
set to adjust the threshold level over the entire range of the input signal, from zero to the maximum level
allowed at the input.
Table 2: Memory Map
Address
00h
01h
...
10h
11h
...
20h
21h
22h
23h
24h
25h
Access
R/W
R/W
...
R/W
R/W
...
R/W
R/O
R/O
R/O
R/O
R/O
Output Y1’s programmed input channel
...
Output Y16’s programmed input channel
Description
Output Y0’s programmed input channel ( write and then assert CONFIG to program)
Internal output Y17’s programmed input channel
...
Internal output Y32’s programmed input channel
Rx Activity monitor for inputs A0, A1,A2,A3
Rx Activity monitor for inputs A4, A5,A6,A7
Rx Activity monitor for inputs A8, A9,A10,A11
Rx Activity monitor for inputs A12, A13,A14,A15
Rx Activity monitor for input A16
( Logic ‘1’=No activity)
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VITESSE
SEMICONDUCTOR CORPORATION
• 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
G52247-0, Rev 4.2
02/09/01
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
