61CI25 View Datasheet(PDF) - Linear Technology
Part Name
Description
Manufacturer
61CI25 Datasheet PDF : 16 Pages
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LT1461
APPLICATIO S I FOR ATIO
relative output deviation is noted. The result shown in
Figure 5a is for two LT1461S8-2.5s mounted vertically and
Figure 5b is for two LT1461S8-2.5s mounted horizontally.
The parts oriented in Figure 5a impart less stress into the
package because stress is absorbed in the leads. Figures
5a and 5b show the deviation to be between 125µV and
250µV and implies a 50ppm and 100ppm change respec-
tively. This corresponds to a 13- to 14-bit system and is
not a problem for most 10- to 12-bit systems unless the
system has a calibration. In this case, as with temperature
hysteresis, this low level can be important and even more
careful techniques are required.
The most effective technique to improve PC board stress
is to cut slots in the board around the reference to serve as
a strain relief. These slots can be cut on three sides of the
reference and the leads can exit on the fourth side. This
“tongue” of PC board material can be oriented in the long
direction of the board to further reduce stress transferred
to the reference.
The results of slotting the PC boards of Figures 5a and
5b are shown in Figures 6a and 6b. In this example the
slots can improve the output shift from about 100ppm to
nearly zero.
2
2
1
1
0
LONG DIMENSION
–1
0
10
20
30
FLEXURE NUMBER
Figure 5a. Two Typical LT1461S8-2.5s,
Vertical Orientation Without Slots
2
40
1461 F05a
0
SLOT
–1
0
10
20
30
40
FLEXURE NUMBER
1461 F06a
Figure 6a. Same Two LT1461S8-2.5s in Figure 5a, but with Slots
2
1
1
0
LONG DIMENSION
–1
0
10
20
30
FLEXURE NUMBER
Figure 5b. Two Typical LT1461S8-2.5s,
Horizontal Orientation Without Slots
0
SLOT
40
1461 F05b
–1
0
10
20
30
40
FLEXURE NUMBER
1461 F06b
Figure 6b. Same Two LT1461S8-2.5s in Figure 5b, but with Slots
11
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