FXO-LC53 Series
MTTF / FITS Calculations
Products are grouped together by process for MTTF calculations.
(All XpressO output and package types are manufactured with the same process)
Number of Parts Tested:
Number of Failures: 0
360 (120 of each output type: HCMOS, LVDS, LVPECL)
Test Temperature: 125°C
Number of Hours:
2000
MTTF was calculated using the following formulas:
[1.] Device Hours (devhrs) = (number of devices) x (hours at elevated temperature in °K)
devhrs× af × 2
[2.] MTTF =
χ2
1
[3.] FITS =
* 109
MTTF
Where:
Label
Name
Formula/Value
eV
k
1 1
)×( −
t1 t2
)
e(
af
Acceleration Factor
eV
k
Activation Energy
0.40 V
8.62 X 10-5 eV/°K
Bolzman’s Constant
t1
t2
Θ
r
Operating Temperature (°K)
Accelerated Temperature (°K)
Confidence Level (60% industry standard)
Number of failed devices
Theta
Failures
statistical significance for bivariate tabular analysis [table look-
up] based on assumed Θ (Theta – confidence) and number of
failures (r) For zero failures (60% Confidence): χ2 = 1.830
χ2
Chi-Square
DEVICE-HOURS = 360 x 2000 HOURS = 720,000
0.40
1
1
(
)×(
−
)
8.625
298 398
ACCELERATION FACTOR =
= 49.91009
e
720,000× 49.91009× 2
MTTF =
= 15,607,065 Hours
1.833
1.833
Failure Rate =
= 6.41E-8
720,000× 49.91009× 2
FITS = Failure Rate *1E9 = 64
Page 14 of 15
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