FXO-LC52
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:
360 (120 of each output type: HCMOS, LVDS, LVPECL)
Number of Failures: 0
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)
[2.]
MTTF
=
[3.] FITS =
Where:
Label
af
eV
k
t
1
t
2
Θ
r
χ
2
devhrs
×
af
×
2
χ
2
* 10
9
Formula/Value
eV
1 1
( )
×
(
−
)
k
t
1
t
2
1
MTTF
Name
Acceleration Factor
Activation Energy
Bolzman’s Constant
e
0.40 V
8.62 X 10
-5
eV/°K
Operating Temperature (°K)
Accelerated Temperature (°K)
Theta
Failures
Chi-Square
Confidence Level (60% industry standard)
Number of failed devices
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):
χ
2
= 1.830
DEVICE-HOURS = 360 x 2000 HOURS = 720,000
(
1
1
0.40
)
)
×
(
−
298 398
= 49.91009
8.625
ACCELERATION FACTOR =
e
MTTF =
720,000
×
49.91009
×
2
= 39,209,238 Hours
1.833
1.833
= 2.55E-8
720,000
×
49.91009
×
2
Failure Rate =
FITS = Failure Rate *1E9 = 26
Page
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