Other Parts Discussed in Thread: LMV358A, LM358LV, , ,
In a sensor project (low cost instrumentation amplifier for pressure sensor in wheatstone bridge configuration) we are using LM2904DGKR but on a batch marked 23TI we had a suspected offset voltage drift in time.
The suspect is a drift in time of the Vos (voltage offset) not out of spec but different from initial value. Drift is in the range of 1-2mV. We asked to Teaxas a failure analisys on the parts and they answered with NTF on the parts (TI QUALITY REPORT 2023-10-05 – Rev. A QEM-CCR-2310-00068 [CPR231088550]). Test A-B-A was not performed because on each PCBA the opamp is connected to a specific wheatstone bridge and individually calibrated, so it is not possible to switch it as the zero offset trimming is unique: moreover the change in drift was not a deviation in time but a sudden change in the offset that afterwards remain stable so it is not recognizable and detectable if assembled on another circuit.
But I want to know if you could provide us more design information, in particular what is the expected drift in time (ageing) of Vos and if you can give us any possible suggestion or hint how to analyze and detect root cause of thsi issue and any possible solution (also suggesting us a possible IC replacement, considering it's a low cost application).
Thank you and best regards.
Fermo Facchetti
R&D Engineer
Kolektor Microtel S.r.l. • Via G. Di Vittorio 5 • 20065 Inzago (MI) • Italy
email: Fermo.Facchetti@kolektor.com
