Browse Prior Art Database

Fault-Tolerant Power Supply

IP.com Disclosure Number: IPCOM000115997D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Newmarch, D: AUTHOR

Abstract

In packaging devices for attachment to a Serial Storage Archictecture (SSA) Interface, a +5 volt supply is required to the 'end of string' connections to drive optical converters as optional features. The SSA link requires each end of the string to have a fault tolerant supply so that if one end fails, access is available through the other (Fig. 1).

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Fault-Tolerant Power Supply

      In packaging devices for attachment to a Serial Storage
Archictecture (SSA) Interface, a +5 volt supply is required to the
'end of string' connections to drive optical converters as optional
features.  The SSA link requires each end of the string to have a
fault tolerant supply so that if one end fails, access is available
through the other (Fig. 1).

      In the device package, voltage is distributed at a bulk DC
level, so +5 volts is not readily available.  To provide a supply
would require a DC/DC converter and associated RAS logic and would
need to be duplicated for fault tolerance.  This adds cost and
complexity to the package.

      The approach described below provides a simple and effective
solution to this problem.

      At each device in the package, the bulk voltage is converted to
+12 and +5 volts for use by the device.  It is ideal to route this
off the device carrier to supply the optical converter, adding no
extra cost to the design, the power required by the converter being
well within the capacity of the device DC/DC converter.

      For fault tolerance, the converter at each end of the string is
supplied by the device at the end; thus if one device failed in such
a way as to remove power from the optical converter, then the
alternate path would still be active from the other device.

      This solution is fully effective when there is a full
complement of devices in the string.  When there is not, the above
remains good if a minimum of two devices are in the string, one at
each end.  This limitation in the use of the string with the optical
converter will meet most applications but is not ideal.  If only two
devices are to be populated on the string it is natural to have them
...