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Chapter 3: Calculating the gain resistor value
The ICA1 and 2 are supplied un-calibrated but optimized for a sensitivity of 2.5mV/V. To accommodate other
sensitivities the gain resistor 'R' as shown in Figure 2.2, can be changed according to the following formula.
N.B. a high quality component e.g. 1% 25 ppm metal film resistor should be used for optimum performance (the 'H'
versions should use 10-15 ppm metal film devices). It may be necessary to use an E96 value to optimise the trim
range:-
Table 3.1 ICA1 (0.1V to 10.1V)
Gain
=
372
(required mV/V)
e.g. 1
For 2.5 mV/V
(Factory setting):-
e.g. 2
For 0.5 mV/V
e.g. 3
For 5.0 mV/V
Table 3.2 ICA2 (0.1V to 5.1V)
Gain
=
186
(required mV/V)
e.g. 1
For 2.5 mV/V
(Factory setting):-
e.g. 2
For 0.5 mV/V
e.g. 3
For 5.0 mV/V
7
Mantracourt Electronics Limited ICA1 and ICA2 S and H Versions User Manual
R
Gain
= 149 x
R= 270 Ohms
Gain
= 744 x
R= 53.8 Ohms
Gain
= 74.4 x
R= 545 Ohms
R
Gain
= 74.4 x
R= 545 Ohms
Gain
= 372 x
R= 107.8 Ohms
Gain
= 37.2 x
R= 1105 Ohms
=
40,000
Ohms
(Gain-1)
(Use preferred value 270R)
(Use preferred value 53.6R E96)
(Use preferred value 549R E96)
=
40,000
Ohms
(Gain-1)
(Use preferred value 549R E96)
(Use preferred value 107R E96)
(Use preferred value 1K1)
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