Redundant Power Supply Management

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LatticeReferenceDesign-LogoOne method used to increase the reliability of high availability systems is though the use of redundant power supplies. These systems are powered by two or more supplies. These supplies are generated either by multiple sources or the system is connected to the main supply by the use multiple paths. Boards, connected to these redundant supplies, derive a single high availability rail through the use of diodes. This arrangement is called power rail OR’ing.

This reference design describes the use of a Lattice Power Manager II device to achieve Redundant Power Supply Management using the power supply OR’ing technique. This reference design is compatible with the Power Manager II Hercules Development Kits.


  • Power Supply OR’ing circuit for 2 supply rails
    • Current sensing for each supply rail
    • MOSFET control to turn on/off each supply rail
    • Programmable SOA and over-current levels
  • 12 Volt Hot swap controller
    • Operate the MOSFET in Safe Area of Operation (SOA)
    • Programmable SOA and over-current levels
  • Seven unassigned VMON inputs available to the user

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Block Diagram

Redundant Power Supply Management

Performance and Size

Tested Devices* Macrocells Product Terms VMONs I/Os HVOuts Timers Revision
ispPAC-POWR1220AT8 17 64 5 0/9 1 2 1.0

* May work in other devices as well.

Note: The performance and design sizes shown above are estimates only. The actual results may vary depending upon the chosen parameters, timing constraints, and device implementation. See the design's documentation for details. All coding and design work was done on a PC platform unless noted otherwise.


Technical Resources
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Redundant Power Supply Management
RD1064 1.0 4/26/2010 PDF 508.9 KB
Redundant Power Supply Management - Source Code
RD1064 1.0 4/26/2010 ZIP 441.3 KB

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