Electronic Design

Mixing And Matching FPA Building Blocks

PRM and VTM devices can be applied in various ways, depending on the requirements for voltage regulation, load current, system cost, and other factors. For example, just one PRM can power multiple VTMs in open-loop fashion to generate multiple supply voltages. The result can be a low-cost, high-density power system (Fig. a).

With this approach, it's also possible to operate one of the VTMs closed-loop with the PRM for the tightest possible voltage regulation at that load. The voltage regulation of the other VTMs will then follow that of the VTM that operates closed-loop. A variation on this theme is to have one of the dependently regulated VTMs supplying dual supply voltages (Fig. b). Cases that demand independently regulated outputs call for multiple PRM and VRM pairs (Fig. c).

One VTM can deliver 80 A at up to 2.5 V, or provide less current at higher voltages for a maximum 200-W output. When higher currents or power levels are required, multiple VTMs can be paralleled (Fig. d).

A single VTM may also be applied in an open-loop configuration with an existing dc-dc converter to provide a POL converter that offers high current density (Fig. e). Adding a feedback amplifier will enable that same VTM to operate closed-loop with the dc-dc converter (Fig. f).

The fast transient response of the VTM even makes it a potential replacement for a conventional voltage regulator module (VRM) used to power a microprocessor (Fig. g). This application will require an additional IC to interpret the voltage identification code (VID) generated by the processor and to adjust the output voltage of the PRM.

When comparing Vicor's Factorized Power Architecture with conventional approaches to distributed power, note the packaging differences between conventional bricks and the V*I Chips. While many bricks require through-hole mounting, the V*I Chips need only standard pick-and-place surface-mount assembly. Their low package height is another distinction. The PRM and VTM stand 0.236 in. off the board with standard mounting and just 0.153 in. when mounted in the board. In contrast, a quarter brick usually stands 0.4 in. or more off the board.

The V•I Chips' BGA packaging also eases thermal management with thermal resistances of 2°C/W junction-to-case and 3°C/W junction-to-pc board. PRMs and VTMs will operate with case temperatures of up to 125°C.

To configure an FPA-based solution, customers will pick V•I Chips from Vicor's PRM and VTM families. PRMs will be chosen based on the input voltage range of the application, the output value required for optimum distribution,and the voltage transformation required for the load. VTMs will then be selected according to the voltage transformation ratio required by the load.

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