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Meeting Military Aircraft Electrical Specifications

MIL-STD-704* came into being to standardize aircraft electrical requirements for the armed services. Since 1959 there have been a number of modifications to this basic specification, with the latest, MIL-STD-704F, being introduced in 2004. Initially MIL-STD-704 limited itself to two basic voltage buses, a three-phase 115Vac (typically 400Hz) supply with limited single-phase loading and a 28V DC system. Over the years there have been many changes in the surge and transient withstand levels, particularly for the 28Vdc rail and the introduction of a 270Vdc bus. Vicor manufactures parts to meet most of these requirements....

Vicor’s Maxi, Mini and Micro modules support paralleling of identical converters to expand the output power. A PR signal is communicated to all modules within the parallel array to synchronize switching frequency. Current sharing is inherent due to the matched power trains of the converters, even under conditions of dynamic loading. In a parallel array, the PR pin function allows only one module to be the Driver; all other modules will automatically become Boosters. Care should be taken by choosing a proper PR-connection. The following application note discusses different ways to connect the PR...

Battery Charger Design Uses Unique Converter Control

A unique converter control scheme for a battery charger uses features on Vicor DC-DC modules to achieve small size and high-efficiency, plus the flexibility to adapt the charger for every input voltage range, battery voltage, and capacity. The design also maximises battery operating life and minimises maintenance costs for offline battery charging off lead-acid batteries. An offline battery charger, based on a Vicor DC-DC converter module and controller IC, provides the flexibility to adapt the design for every input voltage range, battery voltage, and capacity. The design also achieves high efficiency as well as...

New Demo Board Eases Accurate LED Driving

The new pre-regulator module (PRM™) demonstration board, from V.I. Chip, delivers constant-current accuracy of 99.7% for lower power consumption LED-driving applications. A standalone PRM provides adjustable non-isolated currents up to 240W (5A at 48V). When combined with a voltage transformation module (VTM™), the PRM produces isolated currents up to 100A using less than 1 W per 1000 Lumens generated. The constant-current PRM™ demonstration board provides precisely-regulated currents for direct-drive multi-LED applications which control LED intensity and brightness by current regulation. The board can be used as a standalone module to provide an adjustable non-isolated current...

Vicor has just launched a major new range of 72V input DC-DC converters for rail and transport applications. Joining their proven 110V modules, the new range introduces the rail industry’s widest choice of DC-DC converters. The new 72V input range features 27 DC-DC converters covering nine standard output voltages over three standard package sizes and three pin options. Power outputs range from 75W up to 400W. The modules meet EN50155 requirements for operating voltage, shock, vibration and temperature, whilst the product platform simplifies thermal management with three proven baseplate designs. The range covers five...

A new family of MAXI MIL-COTS DC-DC converters allows designers to specify one converter for 12V and 24V vehicle battery systems. The 28V DC-DC Maxi converters feature a wide input range of 10V to 36V with eight different output voltage options and maximum power of 200W. Full encapsulation, using Vicor’s proprietary spin-fill process, ensures void-free encapsulation which protects the modules even in harsh environmental conditions.

Droop-Sharing in a Compact Satellite Up-Link

Droop-sharing is often the easiest and most reliable method of producing a redundant bus onto a backplane of a rack-based system. The method not only eliminates the need for a complex and vulnerable communications bus between PSUs, but also allows the backplane bus voltage to be further stepped-down to lower voltages to remove the need for absolute and precise regulation. These advantages, in conjunction with Vicor VI DC-DC converters, are being used in a compact satellite up-link, capable of fitting into a 3U rack. The up-link required a distributed bus of +7.2V at 12A...

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Meeting Military Aircraft Electrical Specifications

Paralleling Outputs

Battery Charger Design Uses Unique Converter Control

New Demo Board Eases Accurate LED Driving

Major New Range of 72V DC-DC Converters

MAXI MIL-COTS DC-DC Converters

Droop-Sharing in a Compact Satellite Up-Link

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