Abstract: Automatic test equipment including a digital test instrument that may test for and respond to over-voltage conditions. Information on over-voltage conditions may be used in detecting or diagnosing fault conditions within a system under test. Over-voltage conditions may be monitored as part of a test to determine the time and the channels on which they occur. A test may fail if an over-voltage condition is detected and the results of the test may indicate when and where the over-voltage condition occurred. Alternatively, indications of over-voltage conditions may be used to alter the test environment. In response to an over-voltage condition, units under test may be disconnected from the test environment to avoid exposing circuitry within those units to voltage levels that may damage or stress components. Alternatively, indications of an over-voltage condition may be used to disconnect from the test environment equipment that may be generating the over-voltage conditions.

Abstract: An interface for a bus test instrument is readily adaptable for testing a wide range of bus types. The interface includes a pair of transmit lines and a pair of receive lines. A transmitting circuit is adaptable for transmitting either single-ended or differential signals over the transmit lines, and at least one receiving circuit is adaptable for receiving either single-ended or differential signals from either the receive lines or the transmit lines. The flexible interface allows the testing of single-ended and differential busses, as well as busses that support both unidirectional and bidirectional communication.

Abstract: A programmable active load is adapted for use with differential signals. The differential active load includes a diode quad having four terminals. A first programmable current source is connected to the first node and a second programmable current source is connected to the second node. The third and fourth nodes are respectively adapted to receive first and second differential signals of a differential pair of signals. The differential active load sources current to the more negative of the first and second differential signals, and sinks current from the more positive of the first and second differential signals.