Commodity design enhanced for high-reliability PSU

Minebea has evolved the elaborate double forward convertor topology used in its standard range of PC power supplies to develop its new Phoenix topology.

Minebea has evolved the elaborate double forward convertor topology used in its standard range of PC power supplies to develop its new Phoenix topology.

A great deal of work has been done to refine and optimise all aspects of the topology.

Two years ago, a patented voltage tracking PFC preconvertor stage was added to the front end of this topology to ensure input harmonic current (EN61000-3-2) compliance.

The combined stage has formed the core of all 250 to 400W power supplies designed by Minebea.

Now, by further magnetic optimisation and the addition of a second parallel FET in the PFC stage the company's engineers have managed to increase the output power of this core platform above 550W.

A second magnetic amplifier postregulator circuit has also been added to the core platform so that each of the output voltage channel has its own control loop.

N+1 redundant operation capability has also been added using the circuitry already employed in advanced resonant (Reliant based) server power supply designs.

Advanced control circuitry enables the Phoenix design to achieve full N+1 redundant functionality using only two magnetic amplifier postregular channels.

According to Minebea, competing devices all require three magnetic amplifier postregulator channels to achieve the same functionality.

A backplane has also been developed for a complete 3+1 redundant system based on the Phoenix platform.

This complete system fits into a 2U (80mm) high rack and is now available as a standard product from Minebea.

Phoenix designs have a low part cost because Phoenix has evolved from, and shares many components with, high-volume low-cost PC power supply products.

Minebea reckons Phoenix is the perfect choice for cost sensitive applications that can tolerate a small minimum load on some power outputs.

The minimum load requirements are very small (eg 0.2A on the 12V output).

The high efficiency, simplicity, high reliability and flexibility of the Phoenix platform make it an ideal work-horse for the server market.

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