Peak current detection in a test instrument for ensuring validity of component test output

In a portable electronic test instrument having measurement circuitry for measuring selected parameters at an input terminal, a method of conducting a component test comprising the steps of:

• providing a pixel-addressable display module for graphic display of measurement scan data;
• receiving an indication that a component test mode is selected;
• responsive to said indication, applying a predetermined, periodic test stimulus waveform to a device under test coupled to the input terminal;
• if the leads are intact (current is not zero), beginning a first voltage scan to acquired voltage scan data;
• after completion of the first voltage scan, conducting a current scan to acquire current scan data;
• after completion of the first current scan, moving the acquired voltage scan and current scan data into temporary buffers;
• then checking for an open lead;
• providing buffer pointers into the temporary buffers for updating a display responsive to the acquired voltage and current scan data;
• repeating said checking for an open lead;
• if an open lead is not detected, repeating said conducting a voltage scan and said conducting a current scan so as to form a new scan data pair;
• moving the new scan data pair into the temporary buffers;
• and
• repeating the foregoing series of steps so that an open lead check is conducted after each scan data pair is acquired.

A test instrument comprising:

• means for generating a periodic test stimulus waveform;
• means for applying the test stimulus waveform to a DUT;
• a single-channel input means coupled to the DUT for performing one at a time of a voltage scan and a current scan to acquire voltage and current scan data, respectively;
• a temporary voltage scan data buffer for holding acquired voltage scan data;
• a temporary current scan data buffer for holding acquired current scan data;
• a set of new display buffers for holding valid voltage and current scan data;
• display means having access to the new display buffers for displaying the valid voltage and current scan data together so as to form a Lissajous-type pattern;
• means for controlling the input means so as to perform a validity check current scan to detect an open lead;
• and
• means for moving voltage and current scan data from the temporary data buffers into the new display buffers for display after completion of the validity check if an open lead is not detected.