Browse Prior Art Database

Zero Current Hot Plug

IP.com Disclosure Number: IPCOM000122038D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Gruber, HW: AUTHOR [+4]

Abstract

When functions are introduced in or removed from a digital system, the arrangement described and illustrated in this article prevents large current surges and arcing without requiring a complete shut-down of the power supply. The arrangement is particularly useful for hot plugging (adding or removing circuit cards).

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Zero Current Hot Plug

      When functions are introduced in or removed from a
digital system, the arrangement described and illustrated in this
article prevents large current surges and arcing without requiring a
complete shut-down of the power supply.  The arrangement is
particularly useful for hot plugging (adding or removing circuit
cards).

      The temporary power for a card to be hot plugged is provided by
regulators on the card (see figure).  These regulators use the
voltages from the board into which the card is to be plugged as
reference voltages.  Close tracking of the card voltages by the board
voltages prior to and during plugging prevents large surge currents
across the card to the board connector.  The card regulators are
powered by a bulk voltage.  They do not supply power to the card
after plugging.  The temporary power is connected to the card by a
hot plug cable which serves to hot plug cards into one and the same
board.

      The described arrangement reduces the voltage difference
between a powered board and a hot plug FRU (field replaceable unit).
It may be used for large current-drawing devices.  The temporary
hot-plug regulators do not need to be designed for high power
dissipation and cooling, as they are active only for a few minutes.
The zero current power condition on the card is monitored such that a
card with power-up problems is not plugged into an active system.