SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
STC enables fetching deterministic ATPG vectors from STC ROM and applies them to the UUT using XoR decompressor. BIST is implemented on the application-critical R5 and HSM cores.
The self-test controller uses the existing compression scan chains and applies the patterns from ROM. The scan chains are further unloaded into MISR during shift out operation. At the end of self test, the on chip MISR signature is compared with golden signature stored in pattern ROM.
The On-Product Multiple-Input Signature Register (OPMISR) is a methodology which moves the test pattern generation on-chip. Logic BIST is implemented on functional partitions (BIST’ed COREs) that are speed-critical and have high gate count.
The MISR test structure modifies the typical fullscan scan chain such that each scan data input internally drives many chains. These chains feed to the inserted MISR structure. The chain's values are captured into the MISR during shift, generating a resulting signature that can be shifted out.
A given Unit Under Test (UUT) is scan-inserted, and the scan chains are hooked to the OPMISR logic. A self-test wrapper is created around the UUT and the OPMISR logic. The inputs to the UUR driving the D pin of flops are overridden with a controllable flop inside the UUT. The outputs of the UUT are isolated by an isolation control signal during the STC operation. These features ensure that the core and UUT are isolated from the rest of the system during the self-test.