Browse Prior Art Database

Thyristor Crosspoint Technique for Both Anode and Cathode Rate Effect Evaluation

IP.com Disclosure Number: IPCOM000052364D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 4 page(s) / 126K

Publishing Venue

IBM

Related People

Benichou, C: AUTHOR [+4]

Abstract

For thyristor matrixes currently used in a Private Automatic Branch Telephone Exchange (PABX), it is important to test each thyristor in order to detect any undesirable firing. For example, if each thyristor of a 144 thyristor crosspoint module is to be tested on an individual basis, 288 measurements are necessary. For cost and time savings, a test technique is proposed which assures both the anode and cathode rate effect test in one step comprised of two operations, the module under test remaining on the same testing jig.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 4

Thyristor Crosspoint Technique for Both Anode and Cathode Rate Effect Evaluation

For thyristor matrixes currently used in a Private Automatic Branch Telephone Exchange (PABX), it is important to test each thyristor in order to detect any undesirable firing. For example, if each thyristor of a 144 thyristor crosspoint module is to be tested on an individual basis, 288 measurements are necessary. For cost and time savings, a test technique is proposed which assures both the anode and cathode rate effect test in one step comprised of two operations, the module under test remaining on the same testing jig.

Fig. 1 shows the schematic general diagram of the circuits. The module to be tested is plugged into a testing jig which allows the test of matrixes of up to 32 x 32 = 1024 thyristors or even smaller matrixes of a different configuration in the same jig.

The gates of the thyristors (marker lines M1 --- M18) are permanently biased.

First Operation: Test of the anodes: Ground is applied to all the cathode lines (K1 --- K32) through the four 8-cathode driver circuits. All the anode lines (A1 --- A32) are commoned to point C, which is in fact a conductive anode plane, through 150 Omega resistors, each representing the equivalent impedance of the extension circuit to the generator. The anode driver sends to the anode lines a very sharp pulse (18 V, 5 ns), while the 27 V driver is inhibited. If only one thyristor of the matrix fires, a current will be established near point C which will be detected by the current probe. As a result, the failing module will be rejected.

Second Operation: Test of the cathodes: Ground is no longer applied to the cathode lines. The 27 V driver then sends a slow pulse (27 V, 1 Vs) to the anode lines, and when established, the cathode driver circuits sharply shift the potential of the cathode lines to the ground potential. In this case, if a current is detected in the current probe, the module will also be rejected.

The basic circuits will be described hereafter with regard to Fig. 2, which shows the details for a fragment (a 4 x 8 thyristor matrix) of the matrix to be tested.

Cathode Drivers: Each of the 32 cathode drivers is composed of a 2N 6659 VMOS device, used in...