Browse Prior Art Database

Method for Displaying Embedded Arrays Using ECIPT Latches

IP.com Disclosure Number: IPCOM000040069D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Lusch, RF: AUTHOR [+2]

Abstract

Electronic chip-in-place testing (ECIPT) drivers were implemented in order to enhance testing capabilities. ECIPT permits the scanning of a chip to obtain its values being driven off chip without physically probing the chip. To accomplish this, a latch is associated with each driver and is wired into a normal level sensitive scan design (LSSD) scan ring . The latch is clocked with an external signal which also causes the driver to go to a tri-state level. This signal is called "scan mode". During scanning, scan mode is in such a state as to freeze the contents of the latch. When not scanning, scan mode looks like a "hot clock", allowing the data at the input of the latch to flush directly through to the driver.

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Method for Displaying Embedded Arrays Using ECIPT Latches

Electronic chip-in-place testing (ECIPT) drivers were implemented in order to enhance testing capabilities. ECIPT permits the scanning of a chip to obtain its values being driven off chip without physically probing the chip. To accomplish this, a latch is associated with each driver and is wired into a normal level sensitive scan design (LSSD) scan ring . The latch is clocked with an external signal which also causes the driver to go to a tri-state level. This signal is called "scan mode". During scanning, scan mode is in such a state as to freeze the contents of the latch. When not scanning, scan mode looks like a "hot clock", allowing the data at the input of the latch to flush directly through to the driver. The method, described here, of displaying the contents of an array takes advantage of the operation of the ECIPT latches. Because the data held in the ECIPT latches will only be used during scan mode, it does not matter that it will not be retained once the scan mode signal is removed. The controls for the display function consist of one scan-only latch L1 (Fig. 1) and one more AND- INVERT M3 added to an existing multiplexer for each bit to be displayed. If there is no existing multiplexer feeding any ECIPT driver, then one will have to be generated. The ECIPT drivers do not need to have any functional connection to the array. Latch L1 must be turned on prior to starting the display procedure and left on until the procedure is complete. This is done using a s...