Browse Prior Art Database

Long Line (NPL) Performance Driver

IP.com Disclosure Number: IPCOM000102520D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 89K

Publishing Venue

IBM

Related People

Gaudenzi, GJ: AUTHOR [+3]

Abstract

Disclosed is an emitter follower long line driver circuit with short circuit and overvoltage protection which demonstrates an aggressive AC performance.

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

Long Line (NPL) Performance Driver

       Disclosed is an emitter follower long line driver circuit
with short circuit and overvoltage protection which demonstrates an
aggressive AC performance.

      The key features of the circuit illustrated in Fig. 1 are
summarized below as Original Equipment Manufacturers' Information
standards and requirements for modules on the communication link
between a channel and I/O control units:
      1.   Circuits must be able to tolerate a short circuit
           without impacting module quality.
      2.   Circuits may be subjected to overvoltage up to +7
           V with power supply on or off and must maintain
           functionality.

      The driver is designed to operate in the network illustrated in
Fig. 2.  The AC performance and controlled slew rate is achieved by
the choice of R1, R2, R3, T1, T2, CF and nodal capacitance at node X.

      The DC up level is established by the choice of power supply
and RT.  The load is split between the three output devices labeled
TL.  The down level is achieved by applying a logical 1 level at node
IN, causing node X and the driver output to be at logical 0.

      Short circuit protection is achieved via the circuitry
consisting of T3, T4, T5, S2, TS, R4 and R5.  When the driver is in
an up level, T2 and T5 are off.  T3, S2 and R4 set a reference
potential at the base of TS which is lower than the voltage at the
bases of the TL transistors. Because TS is emitter coupled to the TL
devices, a current switch...