发明名称 |
Apparatus and method for sensitive circuit protection with set-scan testing |
摘要 |
A set/scan test capability is provided for a circuit that includes sensitive subcircuits, but that can be latched out to prevent reverse engineering the sensitive elements. A mechanism to inhibit set/scan test access to at least some of the sensitive subcircuits is selectively actuated by a control circuit to override a normal set/scan test and inhibit set/scan access to the sensitive subcircuits. Various implementations are possible, such as fusible-link PROMs for irreversibly inhibiting set/scan access to the sensitive subcircuits after an initial non-inhibited test period, the use of encryption codes to enable repeated set/scan access to the sensitive subcircuits, and an erasable/reprogrammable mechanism for inhibiting set/scan access to programmed sets of subcircuits. |
申请公布号 |
US5357572(A) |
申请公布日期 |
1994.10.18 |
申请号 |
US19920949281 |
申请日期 |
1992.09.22 |
申请人 |
HUGHES AIRCRAFT COMPANY |
发明人 |
BIANCO, MARK E.;DWYER, DOUGLAS A.;KNOBBE, DAVID J.;BAUKUS, JAMES P.;KRAMER, ALLAN R.;OZDEMIR, FAIK S. |
分类号 |
G01R31/317;G01R31/3185;(IPC1-7):H04L9/00 |
主分类号 |
G01R31/317 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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