Weathering the storm: The trials and tribulations of a digital test instrument

Modern automated test equipment (ATE) is often faced with the challenge of surviving harsh conditions introduced by the user, the unit under test (UUT), and the environment. The individual channels on the ATE are often exposed to over-voltage stress conditions, over-current stress conditions, as well as high temperature operation. Many external forces can generate these extreme conditions. Unfortunately, in the world of digital test, the ATE is often testing a bad UUT. A test instrument design that considers the possibility of exposure to these extreme conditions can substantially increase the mean time to failure (MTTF) of the test instrument. This paper describes design techniques that can be used to enable the digital test instrument to better endure these stresses, and thereby improve its long-term reliability. The paper focuses on design ideas for each of the three aforementioned stress conditions.