Browse Prior Art Database

ISDN Network Power Sensing

IP.com Disclosure Number: IPCOM000121649D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Hardman, BA: AUTHOR

Abstract

Disclosed is a method and circuitry for the implementation of power source sensing by devices or adapters attached to the ISDN communications network.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

ISDN Network Power Sensing

      Disclosed is a method and circuitry for the
implementation of power source sensing by devices or adapters
attached to the ISDN communications network.

      Implementation of power source sensing for ISDN networks must
operate under the following parameters:
      1. Network source voltages between 28 and 58 volts of either
polarity.
      2. Three milliwatts maximum power consumption.
      3. Network-to-adapter isolation up to 3500 volts.
      4. Accept power outages of up to 500 milliseconds without
detection.
      5. Provide a nominal TTL level output signal to the adapter
indicating power on or off status.

      The circuit shown in the schematic meets the above requirements
with minimal cost and component count.

      The network side of the circuit uses a 2N6028 programmable
unijunction transistor (PUT) operating as a relaxation oscillator.
Power is supplied by the ISDN power source through a bridge rectifier
to accommodate voltage polarity reversal.  The high impedance of the
circuit keeps the power consumption below the 3-milliwatt maximum.

      The oscillator pulses are coupled via a H11AV1A optocoupler to
the adapter side, providing the necessary isolation.

      The adapter side of the circuit consists of a 74LS123
retriggerable single-shot to meet the network power source dropout
protection requirement and provide the power on/off TTL level signals
to the adapter circuitry.

      The power to operate the network side of the circuit is derived
from the ISDN network and can vary from a low of 28 volts to a
high of 57...