Patent ID: 8484481

Claim:
A system for implementing a chip lockout protection scheme for an integrated circuit (IC) device, comprising: an on-chip password register that stores a password externally input by a user; an on-chip security block in communication with the password register, the security block configured to generate a chip unlock signal, the value of which depends on whether the externally input password by the user matches a correct password for the IC device; an on-chip false data generator in communication with external data inputs to the IC device; an input protection scheme in communication with the chip unlock signal, the input protection scheme configured to gate the external data inputs to functional chip circuitry upon entry of the correct password; an output protection scheme in communication with the false data generator and the chip unlock signal, the output protection scheme configured to steer true chip data to external outputs of the IC device upon entry of the correct password, and to steer false data generated by the false data generator to the external outputs of the IC device upon entry of an incorrect password; wherein the false data generated by the false data generator is deterministic and based upon external data inputs to the IC device, thereby obfuscating whether the user has actually entered the correct password or not; an on-chip false scan test path, in addition to a real scan test path; wherein external scan-in test data is gated to the real scan test path by the chip unlock signal upon entry of the correct password, the external scan-in test data also coupled directly to the false scan test path; and a multiplexing device controlled by the chip unlock signal, the multiplexing device configured to steer data from the real scan test path to an external scan-out output of the IC device upon entry of the correct password, and configured to steer test data from the false scan test path to the external scan-out output of the IC device upon entry of an incorrect password.