Recently there has been an increase in the demand for high temperature electronics from industrial applications in the aerospace, avionic, automotive, oil exploration and military sectors of the marketplace where devices are required to operate at elevated temperatures without cooling. In order to ensure the reliability of these devices it is essential, not only to test them in an environment which is similar to their operational conditions but also to stress test the devices in order to identify potentially weak devices before they are used in the field. Premature failure of devices in the field can be extremely costly particularly in, for example, ‘down the well’ applications in the oil exploration industry where disruption to oil production can cost a company millions of dollars per hour.

LOCHITT is a PC based benchtop low cost instrument which can be used as the central component in a high temperature test system. It can perform both current and voltage tests on logic, analogue and memory devices, being configured into a pattern generator, logic analyser, data acquisition system as required. The versatility of the system in performing a wide range of customised test and measurement functions is obtained from the adoption of the ‘virtual instrument’ concept embodied in LabVIEWTM.

The system is ideally suited to perform ‘dynamic burn-in’ where devices are continuously stimulated by test patterns more intensively than in normal operating conditions. Consequently the reliability of semiconductor systems can be established without tying up expensive ATE for long periods of time; this would not only be costly but also impractical.

The system features a modular architecture and when configured as a pattern generator, a logic analyser or a data acquisition system it can perform:

• “Current Ratio” measurements
• Memory tests
• Scan tests
• Dynamic Burn-in
• Analysis of HT test runs
• Basic tests on ADCs/DACs

The architecture of the LOCHITT system is centred around the concept of a Virtual Instrument (VITM). In essence a VI is a
computer-based instrument using modular hardware combined with software algorithms to create the functionality of an instrument.

To facilitate the generation of test patterns, a DWE (Digital Waveform Editor) and AWE (Analogue Waveform Editor), developed by National Instruments, are employed in LOCHITT. DWE is a software tool for creating, displaying and editing digital patterns. Digital patterns can either be created within the system or imported from a logic simulator vector files with VCD (Value Change Dump) or ASCII format. A wide variety of commonly used data patterns, such as counter, PRBS and fill-in-values, are built into the DWE to further simplify data creation. Basic editing functions such as cutting, copying, pasting, inserting and deleting are also supported. The edited pattern can be exported into LabVIEW™ with HWS (Hierarchical Waveform Storage) format by default. Waveforms stored as one type with HWS format may be read back as another type. Consequently it provides a greater flexibility with respect to the file manipulation in the system. Furthermore, HWS make it possible to interface 64bit DLLs with LabVIEW™ which is a 32-bit application programme.

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