Mechanism to Merge Manufacturing and Engineering Start Up and Debug Activities With Functional LSSD Strings
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
This article is related to the use of LSSD (Level Sensitive Scan Design) strings at multiple levels: testing during manufacture, start up by development engineering, and operations in the field. Only one pair of scan data lines per card and one pair of scan data lines per chip are used, whereas any combination of strings can be selected. In particular, in any chip, string 0 can be selected. String 0 is by convention a string with no latch at all. It is just a bypass of scan-in and scan-out lines. Another particular case is the string containing all the latches of the chip. If every chip presents all its latches, then the card string will be the string containing all the latches of the card, that is, the manufacturing string. A card with chips arranged thereon is shown in the drawing.