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System for Connecting and Disconnecting Circuit Cards Under Load Without Producing Transients on the Data Bus

IP.com Disclosure Number: IPCOM000046265D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bellamy, PD: AUTHOR [+2]

Abstract

In order to disconnect a circuit card from a data processing apparatus without disconnecting other operating cards, a portable auxiliary power supply is connected to the power terminals of the card and the voltage of the auxiliary supply is gradually raised to the voltage of the normal power supply so that the electrical load is shifted from the normal supply to the auxiliary supply and the current in the card contacts is reduced to about zero. The card is then removed without interrupting current at its power contacts and without producing electrical noise on the power bus. Before a card is plugged into an operating device, the auxiliary power supply is first connected to the card to raise its voltage to the normal operating voltage.

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System for Connecting and Disconnecting Circuit Cards Under Load Without Producing Transients on the Data Bus

In order to disconnect a circuit card from a data processing apparatus without disconnecting other operating cards, a portable auxiliary power supply is connected to the power terminals of the card and the voltage of the auxiliary supply is gradually raised to the voltage of the normal power supply so that the electrical load is shifted from the normal supply to the auxiliary supply and the current in the card contacts is reduced to about zero.

The card is then removed without interrupting current at its power contacts and without producing electrical noise on the power bus. Before a card is plugged into an operating device, the auxiliary power supply is first connected to the card to raise its voltage to the normal operating voltage. This operation charges the decoupling capacitors on the card and prevents electrical noise that otherwise occurs on the power bus when a card is first plugged into the apparatus and the decoupling capacitors draw a heavy charging current. In one version, a diode in the power circuit of the card isolates the auxiliary voltage on the card from the normal voltage of the power bus when the card is being removed. In another version, the voltage drop across the resistance of the power connectors is monitored to detect when the load current has been reduced to a value that is low enough to remove the card without causing a signific...