Power-down integrated circuit built-in self-test structures

Built-in self-test structures composed of logic elements are isolated from the host circuitry by means of separate Test VDD, so that it appears as an open circuit during normal operation of the IC. The separate Test VDD is employed to re-configure the host circuit and operate the test circuitry in the test mode. When Test VDD is removed, the test circuit powers down and disconnects from the host becoming invisible to the normal operation of the IC.<
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