Browse Prior Art Database

Power Supply Control via Monitoring of Communications Signals

IP.com Disclosure Number: IPCOM000115362D
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Landers Jr, JD: AUTHOR

Abstract

Described is a method for automatically controlling the on/off state of a power supply via monitoring a bipolar communications signal such as a RS-232 type signal.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 79% of the total text.

Power Supply Control via Monitoring of Communications Signals

      Described is a method for automatically controlling the on/off
state of a power supply via monitoring a bipolar communications
signal such as a RS-232 type signal.

      Consider a system shown in the Figure where a device such as a
PC drives an external device via a serial interface.  This external
device has a remotely located power supply.  It is desired that this
power supply automatically turn on when the PC is talking to the
external device, and that the power supply turns off when the PC is
turned off.

      The power supply passively monitors the communication line that
is use to drive the external device.  The communication line is a
RS-232 signal line that represents data in a bipolar manner, that is
with valid states being a certain amount above 0V and a certain
amount below 0V.  The state between the two minimum levels is known
as the transition region.

      During normal operation, the communications signal switches
between the valid states.  This means that the signal is in the
transition region for the rise or fall time of the signal, but this
typically is less than .1% of the highest switching speed of the
line.  The power supply circuitry senses this signal being in the
known states and turns the power supply on.

      When the communication line goes to 0V and stays there, this is
indicative of the hardware (PC) driving the communications line being
turned of...