Application information

TSX920, TSX921, TSX922, TSX923

18/32

DocID024310 Rev 4

5.4

Input offset voltage drift over temperature

The maximum input voltage drift over the temperature variation is defined as the offset

variation related to offset value measured at 25 °C. The operational amplifier is one of the

main circuits of the signal conditioning chain, and the amplifier input offset is a major

contributor to the chain accuracy. The signal chain accuracy at 25 °C can be compensated

during production at application level. The maximum input voltage drift over temperature

enables the system designer to anticipate the effect of temperature variations.

The maximum input voltage drift over temperature is computed using Equation 1.

Equation 1

with T = -40 °C and 125 °C.

The datasheet maximum value is guaranteed by a measurement on a representative

5.5

Long term input offset voltage drift

To evaluate product reliability, two types of stress acceleration are used:

Voltage acceleration, by changing the applied voltage

Temperature acceleration, by changing the die temperature (below the maximum

junction temperature allowed by the technology) with the ambient temperature.

The voltage acceleration has been defined based on JEDEC results, and is defined using

Equation 2.

Equation 2

Where:

β is the voltage acceleration constant in 1/V, constant technology parameter (β = 1)

The temperature acceleration is driven by the Arrhenius model, and is defined in

Equation 3.

Equation 3

Where:

∆V

io

∆T

ma x

V

V

–

T

25 °C

–

=

°C

A

FV

e

β V

S

V

U

–

.

=

A

FT

e

E

a

k

------

1

T

U

1

T

S

–

=

.