Gain Error (%) = 100

(100

Gain Error Factor)

-

´

F

2500

(3 R )

2500

u

F

1000

R

1000

F

10000

(9 R ) 10000

u

F

25000

(21 R )

25000

u

21

INA181

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Application Information (continued)

With the adjustment factor from Equation 5, including the device internal input resistance, this factor varies with

each gain version, as shown in Table 1. Each individual device gain error factor is shown in Table 2.

Table 1. Input Resistance

PRODUCT

GAIN

INA181A1

20

25

INA181A2

50

10

INA181A3

100

5

INA181A4

200

2.5

Table 2. Device Gain Error Factor

PRODUCT

SIMPLIFIED GAIN ERROR FACTOR

INA181A1

INA181A2

INA181A3

INA181A4

The gain error that can be expected from the addition of the external series resistors can then be calculated

based on Equation 6:

(6)

For example, using an INA180A2 and the corresponding gain error equation from Table 2, a series resistance of

10 Ω results in a gain error factor of 0.991. The corresponding gain error is then calculated using Equation 6,

resulting in an additional gain error of approximately 0.89% solely because of the external 10-Ω series resistors.