| 摘要 |
In order to enhance the reliability of a built-in test system, a confidence check circuit is connected to the logic and condition sensors of the system in order to test for the proper system operation. The confidence check circuit includes a ring counter which sequentially applies check signals of sufficient magnitude to each of the condition sensors to simulate a condition exceeding acceptable system operation limits resulting in the activation of an appropriate failure indicator associated with the built-in test system if the system is operating properly. A check signal is applied to each condition sensor and verification logic within the confidence check circuit responds to the activation of the correct failure indicator by incrementing the ring counter so as to generate a check signal for the next condition sensor in the confidence check sequence. If the correct failure indicator is not activated the ring counter will not be incremented and the confidence check circuit will time out giving an indication of a failure in the built-in test system or the condition sensors.
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