AD22001N データシートの表示（PDF） - Analog Devices
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AD22001N Datasheet PDF : 8 Pages
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AD22001
resistance track. Bends in the track make the effective L/W more
difficult to calculate, however, certain common cases have been
evaluated.
To calculate the resistance of a track of width W with a 180°
bend at radius W/2 resulting in a spacing W, add a resistance
equivalent to 2.96 squares to account for the bend. Solving the
resistance equation for L/W,
L/W = R/ρS = 10.769 mΩ/0.25 mΩ/sq,
or L/W = 43 squares.
Subtracting out the bend, the remainder is 40.04 squares.
Converting this to linear dimensions gives 4.004" at W = 0.1".
Assuming equal linear sections, the contacts and the bends
should be made at spacings of 3.412"/4 = 0.853", as shown in
Figure 6.
FROM SWITCH
0.853"
0.1"
0.05"
0.1"
0.1"
AD22001
(Not to Scale)
4
5
2.002"
0.1"
0.1"
0.05"
0.1"
AD22001
(Not to Scale)
4
5
TO LAMP
2.002"
Figure 5. PCB Track Shunt Resistor with One 180° Bend
As shown in Figure 5, the contacts are made to the resistor
section of the track at 2.002" from the bend. The bend has a
uniform width of W, which is 0.1" in this case, and a radius of
W/2. As a result, the aspect ratio of the straight sections plus the
bend total 2.96 squares + (2.002" + 2.002")/0.1" or 43 squares.
The straight sections need not be of equal length, so long as
They have the proper total, and the shorter one is longer than
about 3W. A shorter resistor can be made by using more bends
and reducing the linear portion. For example, with three bends
the total length of four linear sections would be:
(43 squares – 3 ϫ 2.96 squares/Bend)W
or (43 – 8.88) ϫ 0.1"= 3.412".
TO LAMP
0.853"
Figure 6. PCB Track Shunt Resistor with Two 180° Bends
A 90° bend with an inside radius of W/2 and a smooth width of
W adds 0.341 squares to the aspect ratio as shown in Figure 7.
Note that the linear measurements are differently made at the
90° and the 180° bend.
Other styles of bend can be used with minor variation in total
resistance, however, we do not recommend the use of sharp
inside corners on high current conductors in general and shunt
resistors in particular. Sharp inside corners result in very high
local current density and poor resistance repeatability.
L1
W
W
W
2
L2
Figure 7. PCB Track Shunt Resistor with 90° Bend
–6–
REV. A
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