Method, apparatus, and computer program product for diagnosing a scan chain failure employing fuses coupled to the scan chain
First Claim
1. A method for performing diagnostics on a scan chain having a plurality of latches, the method comprising:
- diagnosing a scan chain employing at least one fuse coupled to at least one latch of the scan chain to load a first logic value into the at least one latch at known location(s) within the scan chain, wherein the at least one fuse couples to the at least one latch at a system port thereof; and
wherein the diagnosing the scan chain comprises unloading logic values from the scan chain, and if the scan chain is broken, localizing a break in the scan chain from the unloaded logic values by comparison thereof with the known location(s) of the at least one latch of the scan chain loaded with the first logic value via the at least one fuse, wherein at least one known location of the known location(s) of the at least one latch is positioned between the break in the scan chain and a scan-out of the scan chain.
1 Assignment
0 Petitions
Accused Products
Abstract
A method, apparatus and computer program product are provided implementing a scan chain diagnostics technique. The diagnostics technique includes employing fuses coupled to latches of the scan chain to load a known logic value into the latches at known locations of the scan chain, and then unloading values from the scan chain, and if the scan chain is defective (for example, based on the unloaded logic values), then localizing a defect in the scan chain from the unloaded logic values by comparison thereof with the known locations of the latches of the scan chain loaded with the known logic value via the fuses. The scan chain may be predesigned with fuses spaced periodically across the chain every n latches to facilitate subsequent localization of a detected defect in the scan chain.
-
Citations
9 Claims
-
1. A method for performing diagnostics on a scan chain having a plurality of latches, the method comprising:
-
diagnosing a scan chain employing at least one fuse coupled to at least one latch of the scan chain to load a first logic value into the at least one latch at known location(s) within the scan chain, wherein the at least one fuse couples to the at least one latch at a system port thereof; and wherein the diagnosing the scan chain comprises unloading logic values from the scan chain, and if the scan chain is broken, localizing a break in the scan chain from the unloaded logic values by comparison thereof with the known location(s) of the at least one latch of the scan chain loaded with the first logic value via the at least one fuse, wherein at least one known location of the known location(s) of the at least one latch is positioned between the break in the scan chain and a scan-out of the scan chain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
Specification