OA1MPA Datasheet, PDF (17/28 Pages) STMicroelectronics – Medical instrumentation

OA1MPA, OA2MPA, OA4MPA
Application information
4.5
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
A_FV
=

e


V_S
–
V_U

Where:
A_FV is the voltage acceleration factor
 is the voltage acceleration constant in 1/V, constant technology parameter ( = 1)
V_S is the stress voltage used for the accelerated test
V_U is the voltage used for the application
The temperature acceleration is driven by the Arrhenius model, and is defined in Equation 3.
Equation 3
A_FT
=
E_--k---a-
e



-_T-¹--_U--
–
T^--1--_S^{--}
Where:
A_FT is the temperature acceleration factor
E_a is the activation energy of the technology based on the failure rate
k is the Boltzmann constant (8.6173 x 10^-5 eV.K^-1)
T_U is the temperature of the die when V_U is used (K)
T_S is the temperature of the die under temperature stress (K)
The final acceleration factor, A_F, is the multiplication of the voltage acceleration factor and
the temperature acceleration factor (Equation 4).
Equation 4
A_F = A_FT  A_FV
A_F is calculated using the temperature and voltage defined in the mission profile of the
product. The A_F value can then be used in Equation 5 to calculate the number of months of
use equivalent to 1000 hours of reliable stress duration.
DocID025992 Rev 1
17/28
28