An apparatus including a test circuit, an output circuit and a control circuit. The test circuit may be configured to generate test data in response to one or more test vectors. The output circuit may be configured to present data in a first mode and prevent presentation of data in a second mode. The output circuit may be configured to switch between the first mode and the second mode in response to a control signal. The control circuit may be configured to generate the control signal according to predetermined criteria for protecting secure data within the apparatus while allowing the test data to be presented.