Special
VPX/OpenVPX on the front lines
VITA 62 brings COTS power supplies to VPX By Patrick Shaw
Though VITA 46 (VPX) and VITA 65 (OpenVPX) systems are rapidly becoming a defense industry mainstay, a system-level interoperability standard for these systems’ power requirements has been a missing ingredient. However, the VITA 62 (Power Supply Modules) working group now aims to fill the void.
VITA 65 (OpenVPX) and VITA 46 (VPX) systems are revolutionizing the defense industry, having overcome initial system-level interoperability issues – for the most part. However, a system-level interoperability void still e xists when it comes to po wer generation for these advanced systems. This gap has led to ad hoc power designs that are system spe - cific but not interoperable between VPX systems. However, VITA 62 (Power Supply Modules) allows systems designs, using OpenVPX as a guideline, to specify power requirements for VITA 62 compatible systems. This will create an ecosystem of many VITA 62 products that are mar - ket driven for the large and growing VPX community.
Accordingly, the VITA 62 working group was started in September 2008 with the support of both module vendors and sys- tem integration companies. (It currently has about 40 participating companies.) The mandate of the committee is to pro - vide a standard set of design guidelines for both hardware and systems to allow vendors to create power supply modules to power VPX systems. The development taking place in the VPX community and in the OpenVPX initiative has primarily focused on the development of modules, slots, and backplane profiles for applica- tions, with little emphasis on ho w these systems are to be powered.
The VITA 62 standard creates a set of design guidelines by which industry power supply vendors can build prod- ucts that will be intermateable to VITA 62-compatible backplanes. OpenVPX currently only refines the power guide- lines defined within VITA 46. It does not address any issues pertaining to po w- ering such OpenVPX systems. When VITA 62 products are later def ined in OpenVPX module, slot, and backplane
profiles, they will allow system archi- tects to specify power requirements for OpenVPX systems.
In addition to po wer conversion/condi- tioning, VITA 62 also defines secondary or utility slots for such system functions as inrush current, output control, Electro- Magnetic Interference (EMI), synchroni- zation, and nuclear detection. VITA 62 has addressed and resolved many of these issues in the current draft, and some high- lights of the accomplishments to date are described in the following sections.
Connectors and pins: Vital to VITA 62 VITA 62 leverages all the ef fort within the VITA 46, VITA 47 (environmentals), VITA 48 (VPX-REDI), and VITA 65 stan- dards while providing a power-generation architecture that fully supports the needs of the critical-systems embedded commu- nity. Key to that goal is VITA 62’s new multivendor connector set for both 3U and 6U modules. The connectors fit into the current VITA 46 mechanical outline, thus facilitating the retrofitting of exist- ing backplanes. The complete connector design, which facilitates efficient power conversion/conditioning, is included in the specification to support multiple con- nector companies’ implementations of VITA 62 connector sets. The connector reuses the same guide pins as defined in the ANSI/VITA 46.0 standard. The pins’ placement, also ANSI/VITA 46.0 compliant, eases modifications of the existing PWB designs to sup- port VITA 62.
The VITA 62 po wer sup- ply connector pin allocation was the main dri ving force in balancing the application’s
20 VME and Critical Systems / Spring 2011
needs versus availability of pins in these new connectors. The 3U posed the greatest challenge with its limited connector real estate. Figure 1 shows the current 3U con- nector set. These samples are being used at General Dynamics Canada to create a set of product offerings for VITA 62.
The VITA 62 pins’ definitions provide a good summary as to the design decisions that have been made in the selection of pins for VPX systems:
-DC_IN/CAN., +DC_IN/ACL CHASSIS,UD1,UD2, UD3,UD4,VBAT,FAIL*,INHIBIT*,ENABLE*,UD0, +12V_AUX,NED,NED_RETURN,3.3V_AUX,
GA0*,GA1*,SM0,SM1,SM2,SM3,-12V_ AUX,SYSRESET*,VS1_SHARE,VS2_SHARE,VS3_ SHARE,SIGNAL_RETURN,VS1_SENSE,VS2_SENSE
VS3_SENSE, SENSE_RETURN, VS3, POWER_ RETURN, POWER_RETURN, VS2, VS1
The VITA 62 committee decided to leverage the VITA 46 P0 utility connec- tor pins to support requirements such as geographical addressing, system management, and other control func - tions while supporting maximum power generation. The connector supports both DC and AC input voltages, with three- phase AC supported only on the 6U con- nectors. The generation of a maximum
Figure 1 | The current 3U connector set for VITA 62
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