Tool/software:
Hi,
I recalculated the MTBF/FIT for component OPA2837IDGKT and it is returning half of the value given by the reliability datasheet.
I believe the equation used by TI is missing a division by 2. Can you please confirm which number is correct?
I have calculated FIT for other TI's part, and looks like my equations are correct. See below:
Thank you.
Ede.
Hello Ede,
For the OPA2837 MTBF/FIT estimates from the estimator tool, you did not use the correct chi-squared distribution function at 60% confidence level.
You used a x2 value for 'zero' failures for CSD18543Q3A. For the OPA2837 estimator outputs, the conditions are for 'one' failure. Your math still used the value from CSD1854Q3A, corresponding to 'zero' failures. You will need to adjust your chi-squared function, which results in a rough factor of 2.
If you properly adjust for the single failure in the OPA2837 case, I believe you will find your results agreeable to the estimator (keeping in mind it is an estimator, not a calculator 
).
Best,
Alec
Hi Alec,
Oopppps....I assumed zero failures straight away as all the other components I am assessing had zero failures. My bad.
Changing the failure to 1 does match. 
Thank you for reviewing it and spotting the mistake. Appreciated.
Ede.
