Sundance SMT373 - Manual (Page 6)

Version 1.8 Page 6 of 15 SMT373 User Manual
Main features
The SMT373 converts Sundance Digital Bus SDB LVTTL signals to Low-Voltage
Differential Signals (LVDS) and can connect two systems several meters apart.
The board operates a conversion between LVTTL (TTL tolerant) signals and Low
Voltage Differential Signals. It provides two bi-directional 20-bit channels that can
transfer up to 2 GBytes/s thanks to 40 SN65LVDM176 transceivers from TI that can
individually reach 400Mbits/s.
Each channel provides 16 bits of data, a clock and a clock-enable signals with their
direction controlled by a single signal. Two other signals can be used for the bus
arbitration in a bi-directional application. The direction of each of them can be
controlled independently.
All the direction control signals are accessible through the connectors and therefore
can be set by the board they are connected to.
The Sundance Digital Bus already provides 200Mbytes/s data transfer rate between
TIMs. Thanks to this module a TIM can communicate with another board several
meters away.
It only requires 3.3V Power supply.
Technical Description
There are two versions of the board, which differ in the way the TTL signals are input.
Version 1: Direct connection. The Mezzanine card is connected PCB to PCB on a
carrier TIM through well-positioned SDB connector as they are on the SMT358.
Version 2: Remote connection. The Mezzanine card is connected through SDB
cables. It only needs the 3.3V provided through the mounting holes.
The board uses LVDM transceivers. They are TIA/EIA-644 standard compliant
devices except that the output current of the drivers is doubled. The board is
compatible with LVDS drivers and has 100
Ω termination resistors. It is compatible
with LVDS receivers because it outputs twice the current of a LVDS driver and
therefor will keep the same voltage for a double terminated line. In half-duplex
transmissions it has the advantage to keep the voltage as in unidirectional
transmissions whereas LVDS would have reduced it by two due to the double
terminated lines.
If the line is not driven or in open-circuit, the output is forced high.