Browse Prior Art Database

Terminator Power Supply for a Small Computer System Interface Bus

IP.com Disclosure Number: IPCOM000106473D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Keener, DS: AUTHOR [+2]

Abstract

Disclosed is a terminator power supply, for attachment to a Small Computer System Interface (SCSI) bus, where the five volts necessary for terminator power is derived from a twelve-volt DC line by means of a five-volt regulator. A thermistor-like device is attached in series at the input of the regulator to limit operation under conditions of an overload, a first diode is attached in series at the output of the regulator to prevent the feedback of current from other power supplies attached to the bus, and a second diode is attached in series at the ground line of the regulator to compensate for the voltage drop in the first diode.

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This is the abbreviated version, containing approximately 68% of the total text.

Terminator Power Supply for a Small Computer System Interface Bus

      Disclosed is a terminator power supply, for attachment to a
Small Computer System Interface (SCSI) bus, where the five volts
necessary for terminator power is derived from a twelve-volt DC line
by means of a five-volt regulator.  A thermistor-like device is
attached in series at the input of the regulator to limit operation
under conditions of an overload, a first diode is attached in series
at the output of the regulator to prevent the feedback of current
from other power supplies attached to the bus, and a second diode is
attached in series at the ground line of the regulator to compensate
for the voltage drop in the first diode.

      As shown in the Figure, a voltage regulator 1, which may be,
for example, a 7805 integrated circuit, produces a potential of five
volts between its output line 2 and its ground line 3, as long as
sufficient voltage and current are supplied through its input line 4.
In this circuit, this input line 4 is tied to a twelve-volt DC power
source at input terminal 5 through a thermistor-like protection
device 6, which is used to limit the current which can be supplied in
an overload condition by increasing resistance with heating.  The
output of this circuit at terminal 7 is tied to a terminator power
line within a SCSI bus through a diode 8, which is included to
prevent the backward flow of current, through the circuit,
originating at another power supply tied to t...