S

3000

Gain Error Factor

R

3000

Gain Error (%) = 100

(100

Gain Error Factor)

-

´

Differential Input Voltage (V)

0

0.2

0.4

0.6

0.8

1

-100

-50

0

50

100

150

200

250

IB+

IB-

20

INA253

SLOS954A – JULY 2018 – REVISED DECEMBER 2018

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Copyright © 2018, Texas Instruments Incorporated

Application Information (continued)

Figure 40. Input Bias Current vs Differential Input Voltage

Calculate the measurement error expected from the additional external filter resistors using Equation 1.

where

•

Gain Error Factor is calculated using Equation 2.

(1)

Where:

•

RS is the external filter resistance value

(2)

Calculate the gain error factor, shown in Equation 2, in order to determine the gain error introduced by the

additional external series resistance. Equation 1 calculates the deviation of the shunt voltage resulting from the

attenuation and imbalance created by the added external filter resistance. Table 1 provides the gain error factor

and gain error for several resistor values.

Table 1. Gain Error Factor and Gain Error for External Input Resistors

EXTERNAL RESISTANCE (Ω)

GAIN ERROR FACTOR

GAIN ERROR (%)

5

0.998

0.17

10

0.997

0.33

100

0.968

3.23