Power supply unit for CompactPCI Serial

March 20, 2014 // By Graham Prophet
Following collaboration with the major board manufacturers, system customers and PSU manufacturers Pentair has created a 'quasi' standard for pluggable Schroff CompactPCI Serial PSUs and developed a first AC PSU with a wide input voltage range. The PICMG has defined the power supply arrangements for CompactPCI Serial as 12V main voltage plus 5V standby voltage.

The form factor, familiar from CompactPCI (19-in., 3U and 8HP), is retained; with an output of 300W, the unit meets the needs of 98% of CompactPCI Serial applications. The PSU conforms to IEC/EN 60950-1 Second Edition, UL 60950-1 and EN 55011/55022 class B. It is pluggable, redundancy-capable and offers quick and easy replacement during system operation if required.

Up to four PSUs can be operated in parallel load sharing is used to divide the overall supply current between the parallel-connected PSUs. Many functions, such as the display of error messages or the sensing of output voltages, have been retained from the CompactPCI. In addition to the FAL and DEG signals familiar from the CompactPCI, a PMBus controller is available so that the PSU can be integrated into system management. This PSU is designed to '80 PLUS' certification. This exceeds the requirements of the 80 PLUS Silver standard and offers efficiencies of 88% at 20% load, 91% at 50% load and 88% at 100% load.

A special power backplane has also been developed for this PSU into which the unit is inserted. The power backplane includes appropriate interfaces to the CompactPCI Serial signal backplane. With this modular concept the PSU can be located on either the right or left in a system which keeps the cabling needed between the power and signal backplanes to a minimum.

The PSU also defines a new connector that features separate AC and DC input pins to prevent incorrect insertion. This means that the high AC or DC power voltages do not have to be carried through the backplane but can rather be fed into the connector direct via these inserted contacts. Costly double-sided insulation of the backplane is avoided, as is the need to cover any exposed AC or DC pins. The connector is designed such that it can carry the required capacity and still offer sufficient free signal pins for additional functions, e.g. communication