Gain Error (%) = 100

(100

Gain Error Factor)

-

´

10,000

(9

R

+ 10,000

´

20,000

(17

R

+ 20,000

´

5000

(9

R

+ 5000

´

10,000

(13

R

+ 10,000

´

1000

R

+ 1000

S

Gain Error Factor =

R

)

(1250

S

´

´

´

R ) + (1250

R

) + (R

R

)

INT

S

INT

INA210, INA211

INA212, INA213

INA214

www.ti.com

SBOS437E – MAY 2008 – REVISED JUNE 2013

The amount of variance in the differential voltage present at the device input relative to the voltage developed at

the shunt resistor is based both on the external series resistance value as well as the internal input resistors, R3

appears as a gain error when comparing the output voltage relative to the voltage across the shunt resistor. A

factor can be calculated to determine the amount of gain error that is introduced by the addition of external series

resistance. The equation used to calculate the expected deviation from the shunt voltage to what is seen at the

device input pins is given in Equation 1:

where:

(1)

With the adjustment factor equation 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

INA210

200

5

INA211

500

2

INA212

1000

1

INA213

50

20

INA214

100

10

Table 2. Device Gain Error Factor

PRODUCT

SIMPLIFIED GAIN ERROR FACTOR

INA210

INA211

INA212

INA213

INA214

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

based on Equation 2:

(2)

For example, using an INA212 and the corresponding gain error equation from Table 2, a series resistance of

10

Ω results in a gain error factor of 0.982. The corresponding gain error is then calculated using Equation 2,

resulting in a gain error of approximately 1.77% solely because of the external 10

Ω series resistors. Using an

INA213 with the same 10

Ω series resistor results in a gain error factor of 0.991 and a gain error of 0.84% again

solely because of these external resistors.

Copyright © 2008–2013, Texas Instruments Incorporated

Submit Documentation Feedback

11

Product Folder Links: INA210 INA211 INA212 INA213 INA214