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EXERCISE 32 : DIGITAL VI (II)
ACTION
Clip on U17. Note the SETUP differences, Voltage range +/- 5V (Normal setup +/- 10V).
Press START on the IC tester and view the traces in comparison to the MASTER traces.
DESCRIPTION
In this test the SETUP has been changed to give a more detailed trace around the +/- 5V
range.
COMMENTS
The traces are made of interpolated points which are sampled by the tester. By selecting a
smaller range you can see more effectively the differences around the diode junctions.
EXERCISE 33 : DIGITAL VI (III)
ACTION
Clip on U10 with the clip reversed. Note the SETUP differences, Connections and V-I selected
in Single.mode Press STARTon the IC tester and view diagram. Click on IC / DV-I button to
toggle between IC Display and V-I traces. Compare to the MASTER traces by clicking on the
MASTER / ACTUAL button.
DESCRIPTION
In this test the SETUP has been changed to allow Power-on tests to be run in conjunction
with Power-off, V-I, tests. Normally the V-I test would require correct orientation of the IC
Clip. In this case the Connections test is carried out to orientate the clip position on the IC, it
is this information that is used to adjust the position of the V-I traces.
COMMENTS
The use of power-on and power-off tests in the same pass is limited to single tests as fast
switching of the power supply may cause damage.
The drawback to using all the tests in one pass may be that the circuit design leaves
capacitors charged up. After the initial power-on phase the caps are discharging into the
tester and so can offset the V-I traces by the amount of charge remaining or give a bad
comparison because the of slight difference in decay time.
In these case it would be better to carry out all power-on tests as a separate step to the V-I
tests.
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