34x34 Crosspoint Switch with Signal Detection
• 34 Input by 34 Output Crosspoint Switch
• 2.5 Gbits/sec. NRZ Data Bandwidth
• TTL Compatible µP Interface
• Differential PECL Data Inputs
• On-chip 50Ω Input Terminations
• 50Ω Source Terminated PECL Output Drivers
• Single 3.3V Supply
• 14W Maximum Power Dissipation
• High Performance 256 BGA Package
The VSC835 is a monolithic 34x34 asynchronous crosspoint switch, designed to carry broadband data
streams at up to 2.5 Gbit/s. The non-blocking switch core is programmed through a parallel port interface that
allows random access programming of each output port. A high degree of signal integrity is maintained through
the chip through fully differential signal paths.
The crosspoint function is based on a multiplexer tree architecture. Each data output is driven by a 34:1
multiplexer tree that can be programmed to one and only one of its 34 inputs, and each data input can be routed
to multiple outputs. The signal path is unregistered, so no clock is required for the data inputs. The signal path is
asynchronous, so there are no restrictions on the phase, frequency, or signal pattern at each input. Each input
channel and each output channel has an signal monitor function that can be used to identify loss of activity
(LOA). An interrupt pin is provided to signal LOA, after which an external controller can query the chip to
determine the channel(s) on which the fault occurred.
Each output driver is a fully differential switched current driver with on-die back-terminations for maxi-
mum signal integrity. Data inputs are terminated on die through 50 ohm resistors terminated to VTERM.
The parallel interface uses TTL levels, and provides address, data, and control pins that are compatible
with a microprocessor-style interface. The control port provides access to all chip functions, including LOA and
programming. Program buffering is provided to allow multiple program assignments to be queued and issued
simultaneously via a single configure command.
VSC835 Block Diagram
G52270-0, Rev. 4.1
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741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896