Cypress Perform

MTBF = Mean time between failures
FIT = Failure in time (number of times an error occurs in one million hours).
MTBF = 1 / FIT

FIT for the CY7B923 is 100FIT = 100 x 10E-9/hour.
So the MTBF = 1/FIT = 1 / 100 x 10E-9 (hours) / 24 (hours/day) / 365 (days/year) = 1141.553 years.
FIT for the Cy7B933 is 100FIT = 30x 10E-9/hour.
So the MTBF = 1/FIT = 1 / 30x 10E-9 (hours) / 24 (hours/day) / 365 (days/year) = 3805.175 years.