OS, T

REF

EXT

worst, T

I

PSRR

CMRR

V

B

S, T

NL

e

(%)

e

e

e

e

e

e

e

'

'

'

OS

REF

EXT

worst

I

PSRR

CMRR

V

B

S

NL

e

(%)

e

e

e

e

e

e

e

T

S

S

S,drift

S,FT

e

(%)

min e

e

* 1000 * T;e

'

ª

º

'

¬

¼

OS, T

OS,RT

OS,drift

OS,FT

I

IN

min I

I

* T;I

e

(%)

I

'

ª

º

'

¬

¼

EXT

EXT

B

IN

B

G

e

(%)

I

REF

S

REF

V

IN

V

RVRR

(V

)

2

S

e

(%)

I

u

S

PSRR

IN

PSRR * (V

5)

e

(%)

I

CM

CMRR

IN

CMRR * V

e

(%)

I

OS

OS

I

IN

I

e

(%)

I

18

TMCS1100

SBOS820 – SEPTEMBER 2019

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Product Folder Links: TMCS1100

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Copyright © 2019, Texas Instruments Incorporated

Application Information (continued)

10.1.1 Total Error Calculation Examples

Total error can be calculated for any arbitrary device condition and current level. Error sources considered should

include input-referred offset current, power-supply rejection, input common-mode rejection, sensitivity error,

sources in percentage terms, as some are significant drivers of error and some have inconsequential impact to

current error. Offset (Equation 15), CMRR (Equation 16), PSRR (Equation 17), VREF gain error (Equation 18),

and external field error (Equation 19) are all referred to the input, and so, are divided by the actual input current

explicitly specified in the Electrical Characteristics table can be used.

(15)

(16)

(17)

(18)

(19)

When calculating error contributions across temperature, only the input offset current and sensitivity error

contributions vary significantly. In both cases, specifications for both the maximum device temperature range and

the parameter drift across temperature are provided. For determining actual performance limits across a

narrower temperature range than the specified –40°C to +125°C, use Equation 20 and Equation 21 for offset

error and sensitivity error, respectively. In both of these calculations, the maximum specified drift for the

parameter can be multiplied by the desired temperature deviation from room temperature (ΔT). Use the smaller

is specified in ppm/°C, and must be converted to percentage error.

(20)

(21)

In order to accurately calculate the total expected error of the device, the contributions from each of the individual

components above must be understood in reference to operating conditions. There are two separate ways to

calculate total error for any particular system. In a worst case scenario, each error term would be at its absolute

maximum with the same polarity. In such a case, the total system error would be a mathematical summation of

each individual error source, as shown in Equation 22 for room temperature. For across temperature worst case

error, the input referred offset and sensitivity error for the relevant range should be substituted in place of the

room temperature values, as in Equation 23.

(22)

(23)