101VMEM105 Bustronic VME Backplane

The Elma / Bustronic J1 and J2 Monolithic Backplanes are designed to maximize performance, minimize noise, and to give the customer the most reliable, cost effective product possible. To achieve this we used 8-layer construction, stripline design, decoupling capacitors at every slot, inboard terminators, heavy power and ground planes, transient analysis simulation programs, and years of experience designing, building, and using backplanes. Although the design could have been done with four layers, we chose to use eight layers so that we could have three layers of ground, two layers of VCC, and three separate signal layers.

Three 2 oz. copper ground layers are used to fully shield the backplane to minimize RFI/EMI emission/susceptibility, to minimize crosstalk, and to maximize power distribution. Furthermore, the outer ground layers serve to prevent signals or VCC from being exposed where they could be shorted or damaged.

Two 2 oz. copper VCC layers are used to maximize power distribution and to act as virtual ground planes for the signals in order to minimize noise and crosstalk. The high frequency decoupling capacitors at every slot and distributed low frequency electrolytic capacitors throughout the board also help this effort. Measured results verify that Elma Bustronic backplanes are among the quietest in the industry.

The combination of multiple heavy layers of VCC and ground and the many distributed the Elma Bustronic backplanes to have superior power distribution as verified by measured comparison with our conveniently distributed power bugs compatible with simple but effective busbars. For lightly loaded backplanes, power can be inserted through the Friction-Lock (AMP MTA) connectors. All status signals such as ACFAIL, RESET, and SYSFAIL are also available on that same connector. Stripline construction is used exclusively for the highest possible performance. By utilizing stripline construction only, we eliminate a severe source of RFI/EMI radiation and make all signals have similar characteristic impedances, virtually identical propagation delays,and minimum signal skew. This in turn allows significantly higher data transfer rates since signal skew factors four times into the transfer rate calculations.