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Circuit Card with Contacts of Five Different Lengths for Gradual Current Change when Card is Plugged in or Unplugged

IP.com Disclosure Number: IPCOM000109123D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Bellamy, PD: AUTHOR [+5]

Abstract

Power to a circuit card is usually turned off before the card is removed from a data processing machine because a voltage spike may be created when current is interrupted to the components on the card. Similarly, power is usually turned off before the card is plugged in to prevent a voltage spike when the uncharged capacitors of the card are connected to the power supply.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 80% of the total text.

Circuit Card with Contacts of Five Different Lengths for Gradual Current Change when Card is Plugged in or Unplugged

      Power to a circuit card is usually turned off before the card
is removed from a data processing machine because a voltage spike may
be created when current is interrupted to the components on the card.
Similarly, power is usually turned off before the card is plugged in
to prevent a voltage spike when the uncharged capacitors of the card
are connected to the power supply.

      This circuit has pins of five different lengths.  In this
description, the pins are numbered 1-5 in the order in which they
make contact as the card is plugged in.  Pins 1-3 establish power
connection through an FET which acts as a resistor.  Pins 4 and 5
establish the normal power connection that bypasses the FETs.

      Pin 1 (the longest pin) establishes the permanent ground
connection for the circuit card.  Pin 2 connects power to the drain
terminal of the FET.  The source terminal of the FET is connected to
supply current to other components on the card.  The gate terminal of
the FET is connected to ground through a resistor network so that the
FET is off while only pins 1 and 2 make contact.  Pin 3 applies a
voltage to the resistor network to turn on the FET.  When the card is
being plugged in, the capacitors are charged at a suitably low rate
through the FET.  Conversely, when the card is being unplugged, the
current to the components is reduced at a...