TDK-Lambda QM Series, Приложения к руководству пользователя

Страница: 35 / 48

QM range App Note, document number 260283, rev 15 Page 35 of 48
9. RELIABILITY
MTBF
Test Specifications: Telcordia SR332 Issue 4, 2016
Test Method: Method I (Parts Count), 90% upper confidence level.
Device Method I-D, Quality II, Electrical Stress 50%.
Results
The failure rates are given for the different sub-assemblies as both mean failure rate and with an upper
confidence level of 90% in the table below at 70°C, 40°C and 25°C.
Assembly
Telcordia SR332 Issue 4 Mean Failure
Rate (FITs
1
)
Telcordia SR332 Issue 4 UCL
2
Failure
Rate (FITs)
70°C 40°C 25°C 70°C 40°C 25°C
QM7 or QM8 EndCap & Fans 932.981 300.000 195.518
1347.091 433.157 282.301
QM7 or QM8 Converter 366.050 120.767 85.757
417.517 131.628 92.506
QM4 or QM5 EndCap & Fans 466.490 150.000 97.759
673.545 216.579 141.150
QM5 Converter 352.518 116.297 82.607
403.496 126.978 89.243
QM4 Converter 338.995 109.437 77.272
389.984 120.060 83.845
T5H or T12H Global Option 269.037 69.324 47.360
306.667 80.196 55.687
T5L Global Option 85.405 18.390 12.109
101.325 20.679 13.565
P5H Global Option 448.181 126.829 89.657
507.434 144.966 104.904
SA Module 257.791 75.691 52.270
302.278 87.476 60.927
≤8V SB or SC Module 391.874 120.833 86.075
445.098 138.202 99.972
≥8V SB or SC Module 400.853 123.523 87.809
454.374 140.961 101.738
DM Module 576.948 202.903 151.994
636.358 225.539 170.575
DH Module 373.969 132.477 98.315
419.809 150.608 113.068
Calculating for a Configuration
To calculate the mean failure rate of a given configuration you can simply sum the mean failure rates of the
constituent sub-assemblies. To convert to MTBF divide one billion (1,000,000,000) by the mean failure rate. To
calculate the upper confidence level failure rate however, simply summing the ULC failure rates gives a
pessimistic result. To calculate it correctly will require contacting Technical Support at TDK Lambda UK, this
can be done for any configuration at any ambient temperature and different confidence levels if required.
Worked Examples
To calculate the reliability at 40°C for the configuration:
QM5FSDL P5H 5SB 12/12DM 12/12DM 24/5DM 24/3V3DM
The F in QM5
F SDL shows this is a unit with built in fan.
EndCap & Fan 150.000
QM5 Converter 116.297
P5H 126.829
5SB 120.833
DM Module ×4 202.903 × 4
Mean failure rate
1325.571
MTBF 1,000,000,000 ÷ 1325.571= 754,391 hours
With an Upper Confidence Level (UCL) of 90% this is 1408.518 or an MTBF of 774,275 hours.
1
FIT’s = Failures In Time. A failure rate of 1 per billion hours.
2
UCL = Upper Confidence Level, for a confidence level of 90%.