White paper VITA-62 6U Power Supply Written by: Jim Russell President, Freedom Power March 2013 Introduction The industry has presented a challenging requirement for a very high power supply combining high power density with high temperatures. This white paper addresses a conceptual design to leverage existing production released products for a new design. The goal is achieve the maximum density possible while meeting the major goals of the application. It will also address potential enhancements that might be possible contingent upon successful completion of newer products from Vicor to achieve even higher power densities. The summary of this design cycle is that we can provide slightly over 1,100 watts of total processing power in the 6U form factor. The design approach presented allows the customer to define the final architecture in combining power chains to archive some granular combinations of nine channels of 110 watts each. Each channel may be specified at design time as either part of the 5 volt output or the main 12 volt output, so long as each channel represents up to 110 watts of total power. There is an additional three channels defined for +/- 12 VDC at 50 watts and 3.3 VDC at 33 watts. Design Concept The block diagram shown in Figure 1 shows the basic concept that was developed: for the MIL-COTS versions of the PRM and VTM when efficiencies are taken into account and power ratings of the blocks, a VTM can safely deliver 110 watts where it is limited by the processing ability of its associated PRM. For a 12 volt output this is 9.33 ADC, for a 5 volt output it is 22.4 ADC. The PRM is the same in all cases but the VTM "K" factor and associated circuitry are selected based on the desired output voltage. The block diagram shows alternating "channels" of 12 and 5 volt power. The voltages are selected based on the customer specification and could be anything of interest within the range of available VTMs. The outputs of some or all of the 5 volt rails can be paralleled, as can the 12 volt outputs. So the customer can specify that the supply be designed for 5 volts at 550 watts and 12 volts at 440 watts, for example. Any combination of 110 watt slices from 0 to 9 may be made. Due to board layout differences for the current levels that will be encountered, it is not desirable to make this factory build option, but should be defined in the board layout. The reason for this approach to the design concept is that it is not feasible, using production released components, to achieve the customer's desired power levels. This would be considered a "Phase 1" release to be used in further system development activities. It allows the system to be tested using the same conversion technology and power supply characteristics that are expected to be carried over into the next generation of even higher density VI Chips from Vicor. vicorpower.com Applications Engineering: 800 927.9474 Page 1 Figure 1. VITA-62 6 U Power Supply, 1,100 Watts MIL-PRM MIL-PRM 5 V, 22.4 A MIL-PRM MIL-PRM 12 V, 9.33 A MIL-PRM MIL-PRM 5 V, 22.4 A MIL-PRM MIL-PRM 12 V, 9.33 A MIL-PRM MIL-PRM 5 V, 22.4 A MIL-PRM MIL-PRM 12 V, 9.33 A MIL-PRM MIL-PRM 5 V, 22.4 A MIL-PRM MIL-PRM 12 V, 9.33 A MIL-PRM MIL-PRM 5 V, 22.4 A 16 – 50 Vin MIL-COTS Cool-Power Converter 12 V, 4.2 A MIL-COTS Cool-Power Converter +12 V, 4.2 A MIL-COTS Cool-Power Converter -12 V, 4.20A The last part of the power chain utilizes new DC-DC converters from Picor. These extremely high power density devices can deliver 50 watts in less than 1 in2. These two parts are used to provide lower power plus and minus 12 volt rails at the 50 watt rating. The last output in the low power section is 3.3 volts at 10 ADC. Since the 3.3 volt CoolPower model is not yet in production release, two Cool-Power parts are used: The same 12 volt converter as above for isolation from the input and a 3.3 volt non-isolated regulator is used for the final step down. Control Elements The power processing part of this application will consume the most of the available room on the card. At the same time, there are two other significant requirements to be addressed: nuclear event detection and protection and VITA-62 bus management. Freedom Power has built other supplies that have incorporated nuclear event protection and has also worked with other customers on incorporating a nuclear event detector. We are familiar with the energy control requirements for managing the rapid shut down of the power supply following a nuclear event. We have also built supplies that contain internal monitoring, reporting, and control functions. The specifics for the VITA-62 version of the controls are new and slightly different but there is nothing that we would consider as a major obstacle in them. vicorpower.com Applications Engineering: 800 927.9474 Page 2 Risk Analysis It will be challenging to fit all the circuits along with an extremely high amount of power into the 6U card space. A preliminary analysis of the layout requirements shows that it is possible. From a risk standpoint, it would be wise to consider reducing the number of "channels" from 9 to 8 if the application power requirements would allow it. That would free up board space for other elements. It should also be noted that this design removes any EMI filtering or transient protection beyond what is inherent in the chip technology in order to pack as much power density into the product as possible. An external EMI filter will be needed. Parameter External Load Capacitance VS1 (12 V) TBD VS2 (12 V) TBD VS3 (5 V) TBD +3.3 V AUX TBD +12 V AUX TBD -12 V AUX TBD Over-Current Limit Under/Over Voltage Trip Point Output Units Min Max Min Typ Max 11 13.2 11.4 12 12.6 Volts DC 125% ±5% 125% ±5% – 25 32 Amperes 11 13.2 11.4 12 12.6 Volts DC 125% ±5% 125% ±5% – 25 32 Amperes 4.5 5.5 4.75 5 5.25 Volts DC 125% ±5% 125% ±5% – 40 45 Amperes 2.97 3.63 3.13 3.3 3.47 Volts DC 125% ±5% 125% ±5% – 3 10 Amperes 11 13.2 11.4 12 12.6 Volts DC 125% ±5% 125% ±5% – – 1 Amperes -11 -13.2 -11.4 -12 -12.6 Volts DC 125% ±5% 125% ±5% – – 1 Amperes Future Developments Currently in the design phase are converters that provide the same types of power levels in half-chip versions. Once these are production ready, then we would expect to be able to increase the power levels and achieve the performance required by the outputs in the customers's thin specification. It should be emphasized that while these products are in development, as with any leading edge product, no commitment is made to availability dates or to final performance parameters. The Power Behind Performance Rev 1.0 08/13 vicorpower.com Applications Engineering: 800 927.9474 Page 3