8.4.4.1 Error Sources

The typical error sources that have the largest effect on the total error of the device are gain error, nonlinearity,

common-mode rejection ratio, and input offset voltage error. For the INA240, an additional error source (referred

to as the reference voltage rejection ratio) is also included in the total error value.

8.4.4.2 Reference Voltage Rejection Ratio Error

Reference voltage rejection ratio refers to the amount of error induced by applying a reference voltage to the

INA240 that deviates from the mid-point of the device supply voltage.

8.4.4.2.1 Total Error Example 1

Table 8-2. Total Error Calculation: Example 1(1)

TERM

SYMBOL

EQUATION

TYPICAL VALUE

Initial input offset voltage

VOS

—

5 µV

Added input offset voltage

because of common-mode

voltage

VOS_CM

´ (V

12V)

-

CM

1

CMRR_dB

20

(

10

0 µV

Added input offset voltage

because of reference

voltage

VOS_REF

RVRR × |VS / 2 – VREF|

0 µV

Total input offset voltage

VOS_Total

(V ) +(V

) +(V

)

OS

OS_CM

OS_REF

2

2

2

5 µV

Error from input offset

voltage

Error_VOS

V

V

OS_Total

SENSE

´ 100

0.05%

Gain error

Error_Gain

—

0.05%

Nonlinearity error

Error_Lin

—

0.01%

Total error

—

(Error_V ) +(Error_Gain) +(Error_Lin)

OS

2

2

2

0.07%

(1)

The data for Table 8-2 was taken with the INA240A4, VS = 5 V, VCM = 12 V, VREF1 = VREF2 = VS / 2, and VSENSE = 10 mV.

8.4.4.2.2 Total Error Example 2

Table 8-3. Total Error Calculation: Example 2(1)

TERM

SYMBOL

EQUATION

TYPICAL VALUE

Initial input offset voltage

VOS

—

5 µV

Added input offset voltage

because of common-mode

voltage

VOS_CM

´ (V

12V)

-

CM

1

CMRR_dB

20

(

10

12.1 µV

Added input offset voltage

because of reference

voltage

VOS_REF

RVRR × |VS / 2 – VREF|

5 µV

Total input offset voltage

VOS_Total

(V ) +(V

) +(V

)

OS

OS_CM

OS_REF

2

2

2

14 µV

Error from input offset

voltage

Error_VOS

V

V

OS_Total

SENSE

´ 100

0.14%

Gain error

Error_Gain

—

0.05%

Nonlinearity error

Error_Lin

—

0.01%

INA240

SBOS662C – JULY 2016 – REVISED DECEMBER 2021

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