Vicor extends ‘component power’ concepts with VIA package
Through a number of generations, Vicor has developed the component power approach, with a front-end module converting incoming supply from AC mains, or high voltage DC, to a system distribution voltage – typically, but not necessarily, 48 VDC. From that level, DC/DC regulator modules, or fixed-ratio converters (“DC transformers”) may supply lower distribution rails, with point-of-load regulators finally supplying PCBs and individual processors, FPGAs and other devices. The architecture allows the designer flexibility in locating conversion, regulation and isolation functions.
The VIA package is superficially not unlike a traditional “brick” format, a module for direct mounting to a heatsink or cold wall. Vicor intends to use it to house input modules for its power architecture; the first product is likely to be a 400W, AC/DC input block. VIA modules will be a standard width and profile of 35.3 mm and 9.3 mm respectively, and will vary in length from 72 to 141 mm. The machined metal housing encloses and provides distribution for one of Vicor’s ChiP units, plus other circuitry.
The ChiP is a recent introduction that hosts a variety of power conversion functions built in an almost totally-automated process. Multiple instances of converters are assembled together on a single large panel, with structural features such as in-board magnetic components that, in the final form, present thermally-conducting faces to both top and bottom of the package. ChiP panels are over-moulded and then sawn – in a similar fashion to a scaled-up silicon wafer – into individual blocks. When used discretely, Vicor adds pins or terminations to the device’s connections – that are exposed on the sawn edges – to allow conventional connections to be made. With appropriate heatsinking to top and bottom of a ChiP package, Vicor quotes over 1 kW per cubic inch power density for a bus-converter (fixed-ratio DC/DC) module.
The company acknowledges that “ultimate” (top and bottom contact, low thermal resistance) heatsinking is not always easy to achieve, which is partly the rationale behind the VIA package. The VIA houses a ChiP module with sufficient space at either end for additional PCB-mounted functions such as EMI filtering, transient protection, or digital bus control/reporting. In the VIA package, the ChiP modules are used without their added pins/surface-mount terminals, direct connections being made to the edge contacts exposed when they are “sawn”. A machined metal housing surrounds the ChiP block, and provides a good thermal path from its top, as well as bottom, surface, to the base plate.
Hinting at future plans, Vicor says that AC/DC and high-voltage-input parts will be standard products, but that its principles of “mass customisation” – effectively, build-to-order – will be carried over from the “brick” product generation into the high-power-density, VIA package format.
Vicor; www.vicorpower.com
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