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1693 RLC Digibridge
7. After biased measurements are completed,
remove all bias by sliding the EXTERNAL
BIAS switch OFF and if necessary pressing
the [SHIFT][INT BIAS] keys, so that the
BIAS ON indicator is NOT lit. Disable the
shorting routine. (See below.)
3.7.3 Suppression or Transients
When measuring biased capacitors, the time required
for settling of transients in the measuring circuitry can
usually be reduced by selecting the automatic shorting
routine (a special function), as follows. Select ENTER
function and press [2] [=][SHIFT][SPECIAL][3].
However, if there is no bias, the normal routine is
faster. To obtain it, select ENTER function and press
[0][=][SHIFT][SPECIAL][3].
NOTE: This automatic shorting routine DOES NOT
discharge the capacitor DUT. It does short a capaci-
tance in the measurement circuit to help terminate
the transient that results from connecting a DUT
with bias.
3.8 Bin Sorting and Go/No-Go Results
3.8.1 Introduction to Binning
(Sorting Based on Limit
Comparisons)
If a group of similar DUTs are to be measured, it is
often convenient to use the limit-comparison capa-
bility of the Digibridge to categorize the parts. This
can be done in lieu of or in addition to recording
the measured value of each part. For example, the
instrument can be used to sort a group of nominally
2.2-uF capacitors into bins of 2%, 5%, 10%, 20%,
lossy rejects, and other rejects. Or it can assign
DUTs to bins of (for example) a 5% series such as
1.8, 2.0,2.2,2.4,2.7 µF, etc, The bin assignments can
be displayed, for guidance in hand sorting. Up to 13
regular bins are provided for categories of the prin-
62
cipal measurement (RLC) , in addition to a bin for
rejects in the secondary measurement (QDR), and a
bin for all other rejects; total = 15 bins.
Manually entered limits are normally entered in pairs
(defining the upper and lower limits of a bin), in the
form of "nominal value" and "percent" above and
below that nominal. If only one "percent" value is
entered for a bin, the limit pair is symmetrical (such as
+/- 2%). To set up a non-symmetrical pair of limits,
two "percent" values must be entered, the higher one
first. Any overlapping portion of 2 bins is automati-
cally assigned to the lower numbered bin.
For simple GO/NO-GO testing, set up a QDR limit
and one regular bin. Entry of limits in additional bins
will define additional GO conditions. Be sure the
unused bins are dosed. (Bins 0 thru 13 are initially
zero, at power-up. This means that the default QDR
limit is "all fail" for D, Rs, and Q with R; it is "all
pass" for Rp or Q with L; and that bins 1 through 13
are initially closed.)
The test frequency can be selected after limits are
entered, before any particular measurement.
3.8.2 Sorting Methods
The figures illustrate 2 basic methods of sorting:
nested and sequential. Nested limits are the natural
choice for sorting by tolerance around a single nomi-
nal value. The lower numbered bins must be narrower
than the higher numbered ones. Symmetrical limit
pairs are shown; but unsymmetrical ones are possible.
(For example, range AB could be assigned to bin 3 and
range FG to bin 4 by use of unsymmetrical limit pairs
in these bins.) Sequential limits, on the other hand,
are the natural choice for sorting by nominal value.
Any overlap is assigned to the lower numbered bin
; any gap between bins defaults to bin 14. The usual
method of entry uses a redefined nominal value for
each bin, with a symmetrical pair of limits. If it is
necessary to define bins without overlap or gaps, use
a single nominal value and unsymmetrical limit pairs.
It is possible to set up one or more, tighter tolerance
bins within each member of a sequence.
Operation
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