CM4 App Note 260424 issue 2.1.docx
Document No. 260424
Page 27 of 29
15. Reliability
The CM4 series has undergone extensive testing, including HALT and Environmental testing. Reliability data is collected on an ongoing basis.
Please contact TDK-Lambda for the most up to date reliability data.
The reliability data quoted in the datasheets are the calculated
failures per million hours
(FPMH) using the Telcordia SR-332, issue 2 standard.
The procedure defined in SR-332 allows several different techniques to be used for calculating MTBF and when evaluating competing MTBF
figures it is important that only the same techniques are compared.
The quoted CM reliability figures use Method I Case 3, Ground, Fixed, Controlled which specifies an ambient temperature of 30°C and an upper
confidence level of 90%. It is also assumed that the product is operated at 100% duty cycle, has an input voltage of 220V
RMS
, an output power of
600W and that the baseplate temperature is the same as the ambient temperature.
The table below shows a summary of the FPMH & MTBF for all system components and for a typical fully assembled system.
Assembly
Failure Rate (FPMH)
MTBF (Hrs)
Input module
0.962972
1038452
Transformer
0.371919
2688754
S1
0.415368
2407499
S2
0.397808
2513774
S3
0.398170
2511487
S4
0.405630
2465300
CM4 with 4 S1 modules
2.996363
333737.934
To calculate the MTBF of any CM system,
Add the FPMH figures for each system component to give the total FPMH.
Get the MTBF by dividing 1,000,000 by the total FPMH.
The variation in FPMH is shown in the graph and table below.
Temp
Input module
Transformer
S1
S2
S3
S4
CM4 with 4 S1 modules
0
0.41329578
0.127619
0.192619
0.185396
0.186105
0.186243
1.291276945
10
0.54688976
0.178886
0.245347
0.235357
0.235992
0.2362
1.678671789
20
0.72397837
0.255159
0.316147
0.302737
0.30326
0.305183
2.206465072
30
0.96297168
0.371919
0.415369
0.397808
0.39817
0.40563
2.951868534
40
1.29407059
0.555049
0.560829
0.538309
0.538452
0.559393
4.046103211
50
1.76616217
0.846405
0.782692
0.754326
0.754185
0.803972
5.707742381
60
2.46010898
1.315415
1.130884
1.095712
1.095216
1.202005
8.299340054
70
3.50420104
2.067304
1.686039
1.643019
1.642101
1.855247
12.39791075
80
5.09894211
3.266645
2.575169
2.523173
2.52177
2.925702
18.91140128
90
7.55815578
5.160517
3.995269
3.93316
3.931214
4.659641
29.23795696
100
11.3495991
8.112606
6.236851
6.163284
6.160733
7.430093
45.4531658
